Sudden FPS problems in SOME 3d instensive games

Hey,

First off sorry if this is the wrong place to post.

A couple days ago I went to a lan party. I took my comp there and back, placing it in the trunk of my car, of which I have 2x 6 by 9 speakers in the parcel shelf sitting about a foot above it. They have large magnets on them. While I was at the Lan we generally played War3~ I played some CoD4 (was a bit drunk) but didn't notice any problems with the fps at all. Once i got home I found that Cod4, AoC and WoW all suddenly started getting really bad FPS. No hardware or software, drivers or anything had been changed. I ran virus scans etc and nothing has showed up. Apart from the FPS problems the computer works fine. I get 200FPS in the CS:S stress test and no problems playing on the net with it either.

Also I should note not even the game settings for any of them have changed either. Especially with CoD4 i find that once i join a game, my ping jumps generally from 25~ depending on the server to 140+ and outside i get 10-30 FPS which for CoD4 and my computer, very bad. Needless to say I have no problems with Starcraft either >.< lol.

These are my specs:
Intel(R) Core(TM)2 Duo CPU E4600 @ 2.40GHz (2 CPUs)
P5K SE
2048MB RAM
Windows XP Pro
nvidea Gigbyte 8800gt 512mb

Hope that helps guys, I'm no computer pro.

i just find it really odd how those other 3d games can perform so badly in game, while actually playing (fine when on menu screens), while CS:S, still a relatively demanding game, can still perform normally. I'm going to try reinstalling CoD4 today. Additionally since the problem, Crysis bugged while loading so I uninstalled that too, lol going to give that another shot as well.

Thanks for taking the time to read this, any help is greatly appreciated.

EDIT: I just reinstalled Crysis and played it on singleplayer, same settings as last time and the FPS problem persists.