Local Disk C is running out of space

Look in your User folders to see what's in each.

If nothing is obvious after going through each, unhide Hidden files in Control Panel>Folder Options>view tab to check size of AppData folders. Delete temporary files in each.

Do you have any kind of Desktop Search installed?
(I had Google Desktop and it created 5GB of index files)

WinDirStat and TreeSize will pinpoint both the files used and their location. Please post those here for identification.

I use this to free up space. Could be windows update backups.

TuneUp Utilities

We have a lot of problems here with tweaking suites like TuneUp Utilities. Win7 is already so lean and optimized that tweaking outside of normal system settings almost always comes back to bite you.

The only cleaner I would use on Win7 is the CCleaner, which is perhaps the most highly regarded app in all of the tech world. http://download.cnet.com/ccleaner/

I have also used free Auslogics Disk and Registry defraggers for over 10 years with excellent results. Others here like Defraggler which is made by the same company which makes CCleaner.

I also use CCleaner and Glary Utilities. Been using Tuneup since 07 and have never had a problem with it.

Game save files. E.g. Oblivion creates VAST amounts of those.

use glary utilities to clear up space.

I had the same problem tonight. (This never happened to me before). I tried disabling hibernation but that only freed 13 of the 100GB the laptop is telling me are full.

It occurred to me system restore could be at fault. I checked the system restore options (Go to start, type "restore point" and click on "create a restore point", then click on configure) and it was set pretty much unrestricted at 99% of my hard drive capacity. I decreased it to 30% and it warned me some old restore points would be deleted to accommodate my new size restriction. I said ok and voila! Now 60% of my hard drive is free. Though this might help somebody.