Drastic FPS drop in TF2 (and Steam games) - Need help

[RPG]

I need some help over here with this.

Yesterday, TF2 was working fine with me, getting its 50-60 fps as usual.
Today, TF2 has been acting up weird on me, starting the round with its normal FPS, and then it reduces to a point were the game is unplayable until I close it. (It takes like.. less than a minute for it to drop)
Not only that, but also my other Steam games suffer this FPS drop (Gmod, Half life 2, Left 4 Dead 2, Poker night at the inventory and Mafia II)

Is other experimating this problem ? or can someone give me a hand here please ?

If it's necessary here are my Pc Specs :
- AMD Athlon II X2 250 Processor 3.0 Ghz
- 2 GB RAM
- 1024 MB GeForce GTX250

[Shadaez]

Most likely over heating, clean the heatsinks with compressed air and clean and reapply the CPU's HSF with new thermal paste.

[RPG]

[QUOTE=Shadaez;29035061]Most likely over heating, clean the heatsinks with compressed air and clean and reapply the CPU's HSF with new thermal paste.[/QUOTE]

Thanks a lot, now it is working perfectly :D