Unable To Open Microsoft Office

I'm not sure what's going on so I'll quickly describe what I've been experiencing. First off, this a three month old computer. I don't use any P2P applications. I'm good at not clicking false links, etc. I'm up to date with Microsoft Updates and all of my software is up to date as well. I ran a virus scan and it came back completely clean. Sunday afternoon, I left my computer up with a bunch of windows open in Google Chrome. Everything was fine. I came back and no web pages would load. I disconnected my ethernet cable and plugged it back in. Everything was fine for a little while. Then everything started getting choppy. Programs were taking forever to open and once they did, the entire computer started lagging. For example, songs in iTunes would pause for about a half a second and jump right back in. It happened almost routinely, every 3-4 seconds. The mouse cursor was also jumping. I restarted and the same effects were observed. I can no longer open any MS Office products. This REALLY screws the computer up. I opened task manager and I can see Powerpoint, for example, running in the background and using about 100kb of memory. "End Process" does not even end the process. I tried using PSKill.exe to kill the process, but to no avail.