I get this strange random mouse lag at easy servers, feels like my mouse lose sens and gets like 60 hz, really annoying. How is this possible? is there something wrong with my setup, or do the servers sux? I have stable ping and fps all the time, even when the mouselags accour...

1280x960 @ 100 hz
500 hz mouse
Mousefix
Windows xp
Services for gaming machine...

If you can reproduce this on suomicom or troopers, then come back with more info.

However, I have pretty good guess on saying server will not affect your mouse settings and/or lag.

My guess is that its not server related, maby it has something to do with my cpu, beeing a amd dual core (i have the fix for this), my graphics drivers or maby ive disabled to many services in win xp... Or maby its just something else

Its something else.
Many ezquake users have mouselags from time to time.