Problems with Video Lag

[Phate]

... at least thats what i think it is. here is the problem as best as i can describe it.

This only happens when playing games, more specifically World of Warcraft. intermittently (about every 5-10 minutes) my FPS goes down from its usual ~20 to about 2. it slows WAY down. but the speakers are still playing normal game sounds (battle, i can tell actions still going on, but cant see it). so i know this isnt a universal computer slow-down, because audio persists at the same speed as normal. also my mouse moves at the normal speed, it isnt locked into 2 fps.

so i heard somewhere someone saying this was video lag, so thats why i made the topic that.

im perplexed as to why this happens, because i have very good equipment.

here is some info to help you out:
Hardware:
NVIDIA GeForce 7600GS video card 512 MB
2gb Patriot Signature RAM
Intel P4 2.4Ghz Processor
Windows XP

ive upgraded it a bit, i think i have an excellent video card, and excellent ram, so im at a loss as to why i get this lag.

the settings im running my games are:
Resolution - 1280x1024
Refresh Rate - 75hz
Colors - highest setting, something about x4 multisampling, 28 bit?

so anyone got any ideas as to why this is happening, or more importantly, how i can fix it?

Thanks,

Phate

[Phate]

anyone got any info on this?