regarding the hard disk space

When Windows 7 installs on your HDD, it creates 2 partitions, as you have noticed. One partition is the [b]System Reserved[/b] partition, and it is approximately 100MB( MegaBytes ) in size. The second partition it creates is your Useful Hard Drive Disk( [b]HDD[/b] ) Space; in other words the space you can use.

I am not sure what you mean by:
[quote]in the ''d' drive i have kept a file of 18 gb valued file. rest is blank means there is more than 80 gb space is available now.[/quote]
I am guessing that you mean - You have an 18GB( GigaByte ) file in your usable Hard Drive section? Which leaves you with 231.9GB of free space.

However you are seeing that as being full? Perhaps you have TEMP files that need to be deleted? OR System Restore Points gone crazy. These files will not show in your Windows Explorer, but will be calculated in your total HDD usage.

You could download CCleaner( FREE ), and use it to "clean" your HDD. http://www.piriform.com/ccleaner

[b]***NOTE[/b]: You should [b][u]NEVER[/u][/b] store anything in the System Reserve, as it is used for... Well, the System. ;-)

I installed TreeSize and discovered :
folder System Volume Information is "Bloated" with multiple entries of same files
(ie. .dll, .exe.cfg,.rbf,.msi,.OLD,.... etc.)in the same folder but different code numbers.
Properties view shows identical info for each type (all .exe with same size are associated with one program.)
This occurred after a noticably long System Restore. I noticed the sudden decrease of free space
There are 18GB.mysteriously consumed.
Is it possible that Sys Restore duplicated these files repeatedly ?
Can I delete these duplicates (all but one in each group)?
i Can't delete all Restore folders except for last one - this is the one that's bloated.
Many Thanks for any help.