i have a 80 gb hard disk and have four partiions C,D,E and F. drive D has a total capacity of 5.85 gb but few days ago i noticed that used space iin that drive shows 4.37 gb but when i viewed the size of all the contents(including hidden files and all that) in that drive it shows only 588 mb. i wonder where has all that space gone ??? is it something due to virus ??

Quite possibly some restore points since they take up space but the amount of space that they take up is hidden unless you break into the restore points folder. Open up system properties, & click on the system restore tab to control which drives/partitions that it monitors/creates restore points for. I only have my OS create restore points for the partition that it is on. What is the format (NTFS or FAT32)?

I'm not allowed to give any kind of advice pertaining to malware so I can't say either way on that question. If you think that it might be malware you need to create a thread under the malware section. Try to turn off restore points on that partition & see how much room that saves.

the amount of space used by the system restore is shown in the system volume information folder isn't it ? the system volume information folder in empty in all the other drives except the C drive ( the drive where my OS is installed ).
i also turned off system restore in the other partitions .

the OS i am using is windows xp professional 2002 and have a 1 gb RAM.

Actually the system restore folders are only empty if there are no restore points however windows by default blocks your access to the system restore folder and because it is blocked you can't tell whats in there or how much room its taking up; windows will tell you that the folder is empty even if it isn't. But if you turned off restore points for a partition then those files should have been erased automatically. Do you know what the file format is for the partition in question?

thanks for the information.
the file system is NTFS.

If you are still missing space I don't know what to tell you except that you could try removing all of your files & reformating the partition. If you have any programs that are installed there then I would uninstall them first. If you don't remove your files they will be erased. Defraging the partition might also help & I would try that first. From my computer, right click on the partition drive letter, click on properties, & then the tools tab. To reformat, right click on the drive letter & then choose format. You shouldn't have to change anything. Don't click quick format. Now click start.

Really this is a "last resort" measure but it should work; you'll get to start over on that partition. There might be something else that you could do however I don't know what. Maybe someone else will have something else to try. Good luck.

One question though, what brand of computer is that? Is it a clone/d-i-y computer or a branded one? Some branded computers would have a partition where a huge portion of space is hidden/missing. Also, if you have either TuneUp Utilities or Raxco PerfectDisk manager you can check them as well. If you do I think I might be able to help out a little.

I just thought of something. Due to cluster size small files actually take up more room on the drive than they actually are. For example a file that's only a few hundred bytes will actually take up 4 kb (4096 bytes) on a partition with a cluster size of 4 kb. So lots of small files could theoretically take up significantly more room on your drive than what it looks like they should. When looking at a file size you should note the "size on disk" instead of the size. Does that make sense? If not just except it as it is because file systems are really complex. Enough so that if you learn how it works you might just wonder how in the world it does work. To save room you can have windows compress files on an ntfs partition. For some files (depending on size & type) this could make the size on disk closer to if not less than (sometimes significantly less than) the actual size. This could however degrade performance. I don't recommend doing this on programs or windows files. Also windows won't let you do this on the system volume files since you are locked out of it. You can also decrease the cluster size when you reformat a partition as ntfs. If you really care to you can research all this for yourself.