Why does my laptop freeze in the middle of something

Your graphics chip is overheating.
This is common problem to many laptops and usually caused by the heatsink having gradualy changed shape so that it no longer sits pressed hard against the CPU/GPU.
Metal is like plasticene in slow motion and the heat sink metal flows around the cpu heat spreader( very rough analogy).
Every such freezing-up you experience, IF CAUSED by this , ( 90% certain) can be solved by crude and simple butchery.
Open said laptop and locate where the relevant chip is ( Intel graphics probably, so NOT the CPU itself) and unassemble the heat assembly( ie unscrew the heatsink thus exposing the heatspreader or the gooey blue cheap thermal gunge/cloth stuck atop the heatspreader.
If you can get hold of more of the same blue gunge/cloth just pack more of the same ( the more the better-within reason) and re-screw the heat sink back as tight as it was.
Basically you need to re-establish the same effective contact between the heat-plate and the heat-spreader as exsisted when the laptop stork delivered it to you.
While you are at it remove all fluff and dirt from your Cooling fans in the laptop as they will be contaminated by normal use.
Your laptop will work properly and for as long as you want it to.
This remedy is for those who are competant working inside a computer.
Laptops are made by ordinary people with two hands like you(and me).
If they can make it you can certainly maintain it.
They were not made by Octopusses(?).
But if you can afford it, send it off and be taken for a ride by many of the so called laptop experts.
They will overcharge you for what is usually a very simple remedy.
As a new Citizen of this Republic Of Technia I feel that it is my duty to encourage my fellow country-folk to have a go.
Please first work on a cheap old Pentium 3 laptop and gain some experience before attempting to work on your own current(and valuable) laptop.
You dont have to fix anything on the old lappie, but just learn dissemble and reassemble it so it continues to work normaly.
If it continues to work then you are doing a good enough job to progress to more worthy machines.
I apologise for the lenght of this reply and did not go into the symptoms of your problem as you have done this enough already.
It seems very like a graphical freeze up as the laptop doesnt overheat and shut down., it just goes solid while appearing to be healthy visualy and aurally( no whining fans).
Good luck.

without knowing the types of files attempted to open or the types of websites
visited. First guess would be maybe you have multiple anti-malware scanners
checking files, or maybe you have some sort of malware infection. The other
guess would be hardware beginning to fail, or loose RAM. Check your add-on
cards to be sure they are fitted, check hard drive for errors, cables worked loose,
and check video card. You might want to scan for malware after booting into
safe mode.

the problem happens at odd times sometime when just trying to open an email or click on a link in a web page or trying to open a saved file on HDD or when trying to play a media file. There is no fixed pattern, I have AVG free version 2011 and also windows defender but that is not active. This problem crept up when my laptop was just new few weeks used and the dealer said that it was low ram problem as I had only 1 gb ram with 256 mb decicated for graphics but upgrading to 2.5 gb ram did not help.

Some people swear by AVG. Me, I say get rid of it. McAfee and Norton are still resource hogs but better than AVG. I had several lockup problems until I get rid of AVG. Could have been a coincidence, but I do not think so.

Also, run Advanced Care System to get rid of the junk on your PC, which accumulates as you use it. The free version is sufficient for my laptops.

switch to win 7

Vista has had stability issues since day1

First and foremost do a full system scan with your antivirus and see if it picks up any type of virus or malware. Once that is complete then it should tell you whether or not you have a virus. Second after the virus scan I would run ccleaner which is a very nifty program it will get rid of temp. files, temp. internet files, cookies and correct any registry errors. that should speed up your laptop a little more not significantly , but it will help. You also might want to get rid of programs that you hardly use which sometimes can slow down your laptop. Also if you can try to upgrade your ram to at least 4 gigs that should improve your performance a little more. If you still do not see any kind of performance increase with those steps then you might want to go ahead and take the advice from some of the posts earlier. Win7 runs a lot smoother then vista trust me on that. Hope this helps and by the way ccleaner you can download for free on filehippo.com.

I suspect a memory issue here. Try Memtest86, or Goldmem offline testers.

Is 2.5 gigs a good figure for memory? I always thought it should be a whole integer.

When things like lock-ups happen at random points, rather than consistently "when I try....", I always look for a hardware explanation. RAM problems is a possibility, but another is thermal problems. Try running "SpeedFan" to chart processor temps. If you are able to see the graph when the lock-up occurs you may see that temp has been increasing to a stupidly high level.

Many Vista era machines will have accumulated enough dust & fluff to totally block the cooling path. Quick easy fix if you are handy with service manual and screwdriver.
Just an idea!

You say that you 'got' the laptop recently.
I dont see how that can be possible that this is- as you describe it - a new laptop as the model came out at least three years ago.
Can you give more accurate story of where the laptop has been for the last two years?
If it is new then none of the answers you were given would be relevant.
If you are in financial services in the middle east I would have thought you could have afforded a much better laptop.
Is there something special about this cheap English laptop that you can share with us all? Lol!
I could also give you a more appropriate answer.

To be honest it really does sound exactly like a problem I had with an Apple Laptop I bought for ??30 about 5 months ago.
It was perfect for 3 to ten minutes and then would freeze but never actualy got hot. Desktop illuminated as normal but cursor frozen and no response from any button.
Anyway it was only after trying the normal suspects that I decided to try the GPU heatsink.
Works perfectly now. Really great little machine.
Sorry Mahmood I am new to this place and I only looked at your profile as you had not bothered to reply to most of the answers so I tried to work out
if you were still around.
As you say the laptop started doing it when it was new then it could be a really nasty reason, that is a loose connection on the motherboard which is just IMPOSSIBLE to locate unless you have the patience of Job.
I would have not bothered doing anything with the thing but got a refund, which as a financial consultant you would arrange much better than I could.
They make great paper weights if you got a really big corporate desk in front of you.

Step (0) is to determine if it's a Hardware or a Software issue. Just boot a Linux Live CD and run that for a while. If the freezes continue, it's a hardware issue. If they go away, it's a software problem.

Hardware Issue -- Most likely overheating, as several here have pointed out. In this case, ensure you use with vents unobstructed, open and clean system with compressed air, if all this doesn't fix it, then reseat the sinks.

But you could have even other problems.... for example, transient memory errors. Test memory with memtest86+ or other exhaustive tester.

Try Hiren's Boot CD to test out other hardware issue possibilities.

Software issue -- Rather random shutdowns within Windows are most likely caused by malware. Download and scan one at a time with various anti-malware products like AVG, Avast, Spybot S&D, Ad-aware, etc, etc.

If the anti-malware route doesn't fix it, you could have registry damage or many other Windows issues. My quick rec is go back to System Restore and LKGM.

Good luck.

I got puzzled by the "the agents/techs couldn't find the problem" ? Did they tell you what they exactly did to even find it ? Did they open the case? Did they re applied thermal paste or cleaned the laptop out for collected dust ? More importantly did you have to part with money for their "opinion".