i've noticed similar behavior while switching between windows, windows media player, photoshop, maya, and mozilla firefox. each program seems to create its own 'mouse speed'.
i have a logitech optical mouse, but without the 'wheelman' drivers installed, because i now have xp and the mouse is USB and a windows update recommended an upgrade that wasn't logitech related.
are you using a logitech mouse, or is it just me? anyone else have a logitech mouse problem?
Accept no substitutions.