Mouse & Keyboard erroneous behavior.

I’ve just formatted and install OS XP with Office XP. My Mouse and Keyboard
behave erroneous every once in a while, especially when I need them the most.
If I click on a message in Outlook all the emails about it are automatically
selected as well. If I’m typing a word document the capslock locks
automatically; the backspace key highlights anything instead of erasing it. I
would have to power down and unplug the a/c cord then plug it back in and
restart my PC and it goes back to normal. Anyone has any comment or
troubleshooting suggestions?

I appreciated all of your help.