Keyboard/Mouse Lockout

[Dark Servant]

I have recently been experiencing what I thought to be freezes.  
However I noticed that programs continued to function normally and 
discovered that unplugging the keyboard and plugging it back in fixes 
the problem.  This fix only works temporarily and the problem occurs 
again after some time.
Problem occurs in various programs and in Finder.
I recently went through disc first aid and repaired permissions 
although I'm not too sure if this is relevant.

Running 10.2.8 on G4-400

Thanks
Ruben A. Franke