I would also like to know the answer to this question.

I have a similar problem. I downloaded something, but noticed my computer started to slow down. So I entered Safe Mode and deleted all the files I downloaded. Things ran fine, but I could still tell something wasn't right. Then I noticed that my memory was being all used up? I think I also contracted a virus. I ran Spybot, and Windows Defender, Defragmented, and am currently doing a disk check. I dunno, just the basic stuff. I'm not much of a computer guy, but yeah.

Also I noticed that when I start up my computer, a small, black, blank MSDOS type window pops up? Nothing's in it, and then it just goes away. I'm certain I don't use alot of memory, because my laptop is fairly new, not much programs on it, except a couple of games and such.

But really, the amount that is being used up is ridiculous! Help please to get my memory back!

I would suggest that you perform a free, online scan to determine if there's an active infection on the system. I recommend these scanners:
http://onecare.live.com/site/en-us/sandbox...s%2Fdefault.htm (requires IE)
http://housecall.trendmicro.com

If the scanners do not completely remove the infection, then I'd suggest starting with the pinned topics in this forum: http://www.bleepingcomputer.com/forums/forum103.html

If you find that you're not infected, please post back and we can work on fixing your Vista installation here.