certain function keys not working on ibm thinkpad T41

i had Norton Antivirus installed, but it kept on launching security alerts. i had no windows automatic update enabled, so i enabled it and download as existing update there was on microsoft’s site. but Norton kept on giving those warnings.
I uninstalled Norton, and then installed NOD32.
since that time (updates installed, norton removed, nod32 installed), my laptop’s function keys are giving me trouble, specificly F5 and F12, which are not working at all. Also when i turn the sound up or down, as well as the brightness, it does not show the progress bar on screen.
What could happen? Can anyone tell me what can i do to solve this problem?
Thanks for your help.