I recently started experiencing this problem, where first after i connect my external hard drive eventually it will tell me i have no space left on drive C...I figured out that for some reason the external hard drive is being copied in a hidden folder in the c:\Windows

I moved the external drive to my desktop where it does the same thing but also the local drives started doing the same...
Anyone have any idea what might be wrong?
I ran virus scans (Using Norton Antivirus) on both the internal and external hard drives and it came up with nothing.

If you can see your ext drive in Explore and Disk Management, does it read and work normally? If it is automatically copying itself to a hidden file in C, that did not happen by accident; it was instructed to and that means possibly there was an option enabled. Did you load any utilities, drivers that came with the drive or possibly something that you loaded via third party at some time in the past? Another way to check is to run a Hijack This log and see if there are any drivers/utilities being loaded on boot that you don't know about. Check the RUN hive in the register for auto loads on boot. You also might run a RUNSCANNER log for a more in-depth analysis (don't delete anything that you don't know what it is!). Do your USB ports run normally other than the ext drive?

I actually figured it out...there was a file called MSTrueCrypt that did all of that...interestingly enough google didn't come up with anything when i searched for it besides a bulgarian website that tells you how another guy got rid of it...it's all fixed now though

thanks anyway

aha! So it was a utility that was doing it. Thanks for posting back.