WIndows XP hangs unexpectantly

If the battery has gone off and will not run the NB for any length of time it may just be the battery needs replacing.

If some RAM has been added recently it could be a timing issue between different speed RAM or even different makes of RAM being slightly different in Specification. To check this you need to test the RAM individually with something like Mem Test on the Ultimate Boot CD

http://www.ultimatebootcd.com/download.html

If both sticks of RAM Pass test again but this time with both sticks fitted. Any failures here will be the result of Timing Issues between the different RAM Sticks Fitted.

You could also try the CPU and other Diagnostic tests on the Ultimate Boot CD to check for problems with the hardware make sure that you check the CPU and HDD for any possible problems.

Also if this is a older NB it may need the BIOS Battery replacing.

Col

I had a PC that would not wake up from suspend
You had to power it off at the wall

The problem was a chipset driver I think
It disappeared after a while
Could have been a background process that was updated
This was on Windows XP

It sounds like a power management problem
But that may not explain the hanging

If it has a system monitor (temperature, fan, voltage) try removing that
I have seen those hang a pc randomly

Check the bios power management settings
Some laptops have very little in the bios setup but you never know