mouse lag in 3D games

hello -

i am having a mouse lag issue when playing unreal gold. it's not jerky lag (movement along axes is smooth), but seems to be delayed a fraction of a section behind my actual mouse movements. here are some points:

- it only lags in fullscreen mode. it doesn't lag when windowed.
- the first unreal doesn't lag AT ALL
- newer games don't have mouse lag in any screen mode (e. g., doom 3, ut2k4). the mouse movement in those games is precise and real-time
- other older games i have seen this with are alice in wonderland and rune

remember, it only does it on certain games in certain modes. here are a few hardware specs:

- p4 2.4 ghz, 1g ram
- radeon x800 8x agp
- corded optic mouse (not wireless)

what i have done so far:

- tried the ATT utility and adjusted the flip queue. did nothing. uninstalled.
- adjusted process priority of game. did nothing.
- reduced game res from 1024x768 to 800x600. did nothing. (remember, it doesn't lag whiled windowed in 1024x768)

question: what can cause mouse lag like this to occur in random games in certain modes?