Cpu Usage is High all of a sudden

I have had Windows 7 Ultimate 64bit running on my Dell XPS 410 for about 3 months now. I have had a few problems, but nothing compared to what Vista put me through. Now all of a sudden, I can't do much multitasking anymore. I have a Evga Nvidia 9500GT graphics card with 1gb ddr2 on it and I use dual monitors. Usually Windows Media Center or Windows Media Player on one and Safari on the other. I have never had a problem doing this before. Even when I had the stock 7300 ls. Now I'm having troubles. My media screen will repeat itself frequently or my browser will hang. When I look at the cpu usage gauge on my widgets it will read something like 95%-100%. All I will have open is Windows Media Center or Windows Media Player and Safari. I have a 1.86 Core 2 Duo and 5gb of pc5400 ddr2 ram. I have made no changes to my system other than formatting one of my hard drives that Windows 7 filled up with backup. I decided that if windows needs more than 500gb of backup then I would rather back my files up manually. Any help is appreciated. Thanks in advanced! -Kevin

Well I tried a system restore and it didn't help. Although, upon further investigation I have found that the program that is causing the problem is called wmpnetwk.exe and it is taking up almost 80% of my cpu. If i close this program through task manager, my cpu will run much faster, however this is only temporary because the program comes back on after a few seconds.

I have run into that issue a couple times. It seems that if you use Media Player sharing in conjunction with Windows Media Center with an Extender such as an xbox, it seems to tax the proc. If you don't use Media Center, then I have also seen it with real time virus scanning or real time anti-spyware causing it to use high CPU. I have noticed more issues with AVG Free and Adaware.

Well that fixed it! Thanks alot Jonathan_King!