theres your problem right there lol
LOL, but i dout it,
Do you have a virus, run the scan just to make sure, you can run free scan using Microsofts Onecare, or download free trial of Kaspersky.
If you have a proper AV Run it,
Also the problem could be that you do not have enough memory to save anymore files, although this is most unlikely. Don't forget Winows reserves some GB for itself.
Also, i know this question is kind of bad in a way but, are you looking in the right folder, i think you are so just to make sure.
Please give more info, you say that you have loaded in something recetly, what was it, after what program did you start to notice the problem.
Also Possible Hard Drive Failure, very bizzare one too. as usually if Hard drive fails it can't do anything.
Well lets see if anybody else has any ides too.