I have two mouse issues.
Slow drag AND fast drag.
The slow drag always happens when I go to the Equip screen. The music starts skipping the same time the mouse does. I have tried turning the music off in the Options screen, but that doesn't help. Some times the slow mouse will also happen in the combat screen, but this is rare compared to the Equip Screen which does it almost all of the time.
The other mouse issue I get is just the opposite, in the combat screen, where the mouse flies across the screen. (Yes, I did adjust the mouse setting in the Options screen, but after not seeing an effect in the Equip Screen, I moved it back to near what it was.) In the combat screen the mouse flies towards whatever side I move the mouse to. If I use the number button to jump to a soldier, if I move the mouse to the left, it flies all the way to the left hand side of the map, making it very difficult to target aliens near the middle of the map.
The biggest issue I have had playing the game, that I haven't seen a bug report on is the fact that the soldiers can end up outside of where the 3d block states that the soldier is standing in. For example, on the Mansion map, I had two soldiers lockup just inside the front door because even though their 3d blocks showed they were standing right next to each other, the graphics of the two soldiers had them sharing the same space, outside of their square (I took a screen shot of this, but I haven't figured out where Vista saved the pic at).
Additionally at the Mansion Map, soldiers on the grand staircase seems to get out of their 3d block quite often. But then this issue seems to happen a lot on stairs.
In the Cave map, on the 1st cave level, behind the staircase going down from the entrance, their is a ledge where you can see and shoot down to the bottom level. Twice now a soldier will get stuck outside of his 3d block, the 3d block will show the soldier at the edge, but the grahic shows the soldier mostly in the square behind that ledge square.
There has been instances where a soldier who is stuck outside of his 3d square will be stuck and even though move commands are given and the TU is expended, the soldier does not move at all.
My system is an AMD Dual Core, Vista OS, 2 gig ram, nVidia 7600GT vid card displayed on a 19" flatscreen LCD.