I'm not sure exactly what triggers it, but when I paint in Photoshop 7 sometimes the brush size will stop responding to my pen pressure (i.e. the brush size will remain constant).
Occassionally I get the problem after alt-tabbing out of Photoshop, but this doesn't happen 100% of the time so I am not sure. I was wondering if maybe there's a hotkey I'm pressing that's killing the pressure sensitivity? Or if there's a quick way to restore it without having to restart Photoshop.
By the way I experience this problem using both my Intuos3 and Graphire3 in Win 2000, XP, and ME. So I'm pretty sure the problem is Photoshop 7.