Yeah it definitely sounds like a virus problem. I had that happen before, you probably need to redo your computer, if not what you should do is turn off system restore in your system options, since from what I heard viruses encode themselves in the files that are used for system restore. After that run a virus scan and clean up anything that it suggests to get rid of. When you're done restart the computer, if that doesn't work then you may have to reformat your O.S., if it's a virus, it's an irc virus, I forget what channels have it, but it infects your program and from there well, everything started getting infected and will stop some programs from running as it will increase the size of the programs by a small degree and since it's not it's original size it's not recognized and it will stop running.