afaik one of the most obvious reason for this is the vertical sync for your monitor/in-game is being turned ON... try to check for both of em.
if u want to turn off in-game sync, say, q3: /r_swapinterval 0

vsync was already off on both my monitor and in-game.
thx anyway :)

First of all, some mice with high USB polling rates are really pain in the ass for some CPUs. When I tried to play Q3 on some brand new dual-core crap with Copperhead, I suffered the same problem. So try to manage USB rate settings and CPU cores. And maybe try to play on your friend's PC.

Second. Try playing another game. If you mouse still moves rapidly (like switching off and on, again and again), I believe it's a warranty case. And you should return the mouse to your retailer.

I'm used to change my mouse cord each third month of playing for same reason.

Are you possibly trying to use 1khz polling? If you are, that might be your main issue. Bump it down to 500hz and you should be fine. Other than that I would say that your computer just sucks.

doesn't matter what hz i use, i've tried 'em all and the problem doesn't go away:/

What sort of mousepad are you using? Is your problem there when you go back to your old mouse?

i use steel series QcK.
no, the problem isn't there with my old mouse, but the problem is only in quake and warsow, not in any other game

What mouse input do you have it using in those games?

i use /in_mouse 3 when i play, and i have tried -1 , 1, 2 and 3 (i use cnq3 1.43 - raw quake 1.0)but there's no difference, mouse lags still there.
same in warsow, no difference between the inputs

Have you tried fresh installs of these games? Fresh configs?

i think that's the only thing i haven't tried.
gonna try that now