[G4] G4 MDD upgrade

[SE]

I recently upgraded the OS on a G4 MDD, 1.2 GHz, 1 GB RAM from OS 10.3.9 
to 10.4.7

The user is now saying she is having problems selecting things with her 
Microsoft, 2-button mouse. She uses Word a lot and claims she cannot 
select a whole line of text the way she has in the past. Also to open a 
document from the desktop double clicking does not seem to work. She has 
to right click and select open from the short cut menu.

I also noticed last week on another client's new iMac running 10.4.7 
that even her new Mighty Mouse seemed to only respond when items are 
clicked on percisely and with a lot of pressure.

Has anyone experienced anything like this?

SE