Help! Something wrong with Time Machine

so, I did my initial (first) backup with time machine on Monday night of 103gb. It went off without a hitch and only took 7 hrs wirelessly, which I thought was pretty good. And it was doing to the hourly backups perfectly. Anyway, I had a major TM malfunction today. TM went to do an hourly back up today, and it just kept going and going and going. I couldn't even open up any programs. Yet, when I would hit >tab, the window said that I had those programs (Address Book, iCal, System Preferences) running, yet they never opened. I went to log out and reboot, yet I couldn't. I had to force quit all applications, then I was able to shut down, only my iMac never shut down. It stayed on a blue screen forever, so I had to manually shut down. So I manually restarted, thought I would give TM another shot just to see what would happen and now it's just running forever again in the "Preparing" stage. The only difference is this time, I'm able to open up apps while it's running. It's been like 20 min now and it's still "preparing"... What's going on? Any help is greatly appreciated as I would love to be able to utilize this app. So weird...