Weird lagging?

[darkskoliro]

Hi, i was wondering if any of you guys have a solution to my problem?
My laptop is and Acer Aspire 5102 WLMi

It has:
Turion TL-50 (dual core)
Radeon x1300 128mb dedicated (512mb hypermemory)
120GB PATA HDD 4200RMP
1.5gb RAM (512mb 533mhz (stock)) + (1gb 667mhz)

And my question is: Why does it suddenly lag sometimes?

In a game, youtube, flash games it just suddenly lags for about....30secs max?
It gets quite annoying when playing fast action games like prototype.

Ive tried everything. Defrag, reinstall and all the other boring stuff you could think about but it just still lags after a while.

 

[darkskoliro]

Forgot. My OS is:
Windows XP Professional SP3
and is also Media Center Edition

 

[frozenlead]

Did you check your temps?

 

[darkskoliro]

For my laptop? Yeah it gets a tiny bit hot but I have a laptop cooling pad which is pretty useful