Shift key not working to constrain type in AI CS3 Windows : Adobe illustrator

I'm encountering a problem in AI CS3 where the shift key has no effect on constraining the scaling of point type.

I've found a few forum posts and a knowledge base article (330664) that describe this problem on Macs, but I'm on Windows (XP SP2).

Also, my problem seems to be specifically confined to point type - and to the use of a Wacom Intuos 3 tablet (with the pen or mouse); while doing troubleshooting I found that the shift key seems to work when I use a regular mouse.

I've deleted the AI prefs quite a few times - and the shift key will work after that for about 3 or 4 operations, but then the problem keeps coming back. I've also re-installed the Wacom tablet software to no avail.

Any help would be appreciated, as I'm currently designing some logos where it's important that the type maintains its proportions.