Keyboard entries sometimes show up as garbage

[chaka]

I have a Dell Inspiron E1505 laptop running Windows XP with service pack 3
installed.
Sometimes the keyboard entries turn to garbage after a few minutes and
sometimes after about an hour. This happens with various programs. Up to now
I just close the particular program and on reopening it things are OK for a
while until it goes haywire again. I have:
1) replaced the keyboard on the laptop

2) worked with my network disabled

3) temporarily disbled my antivirus program (Norton 360)

4) worked in safe mode

Nothing has helped.
Would appreciate any suggestions

 

[Leonard Grey]

And, of course, everyone knows what "turn to garbage" means.