My PC is showing the HD free space wrong, I have some 80GB of stuff, and my PC has 250GB of total space, is showing 7GB, 20GB the other day …
My PC:
Vista 32bit Ultimate Service Pack 2
Intel Core 2 Duo 2.53 GHz
Video Card ATI HD4650 512MB
Motherboard DDR2 667MHz
There’s your problem.
Upgrade to Win7 immediately.
Or downgrade to XP. Keeping Vista is not an option.
I had Vista x64 for about two years without ever having any problem.
No idea about your problem though. I suggest you try google.
Chances are, he does not have permission to access it, what with being on Vista.
I will think in Win7
It may be a hard drive failure, run a disk check 
{80GB of stuff, and my PC has 250GB of total space, is showing 7GB, 20GB}
Alright, 250GB hard drive, or 250GB of reported total capacity?
250GB hard drive will end up being ~230GB once Windows addresses all the space. 230-80 = 150GB maximum free space. Take away the swap/page file, System Restore, temporary internet files, the Windows Temp folder, hibernate file, and other junk, and I’d bet you’re down to at least (most?) 100GB, depending on how often (if ever) you clean your drive, how many System Restore points you have, etc.
Step 1 - download CCleanerand run it - it will clean the useless crap off your harddrive
Step 2 - download WinDirStatand run it - it will tell you the storage used by all files/folders on your drive
Step 3 - upgrade to Windows 7 as previously mentioned 
- Windows Vista has issues with displaying the right amount of freespace.
Vista is Vail, Vupgrade to Vin7.
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