Hard disk space

Have you perhaps 'deleted' some files but never actually emptied the Recycle Bin ?

Are you saying your ENTIRE HDD is 15GB or is it just a 15GB partition on a larger HDD ? If it is only a partition, what size is the entire HDD and how many other partitions does it hold ?

Does your HDD have a Recovery Partition that may exist within the hard drive area you are presently examining - that would account for a chunk of unseen occupancy.

Also, whatever changes you have made to your Page File and the Hibernation routine will NOT take effect on available free space until you have rebooted the system.

System restore can easily use up 14gigs of space eventually, try turning the value down.

I know Win95 did the same damn thing, never did figure it out, entire drive showed only 1 gig used if you selected all files, but the drive reported 2.5 gigs used.

I think filesystem size also makes an impact, but I am not sure. Also the difference between size and size on disk make a big difference. I had some games that made like 8k 10byte files (X-com UFO defense was bad for this), Which took 32kb each on disk. That is 250MB used right there, even though the total size of the files is only 78kb??? (My math is probably wrong).

30 to 50 GB is more appropriate. This provides ample space for service packs, hotfixes and free space for virtual memory as well as space for applications that write files to the system drive even though you install the application to a different partition.

you might try doing disk cleanup and deleting setup files to free up some space

It's possible that with the wrong type of Partition you are experiencing a lot of Slack Space which could be contributing to this issue.

Col