calling all computer nerds!!, avast & vista Options

[jason]

windows vista home premiumavast 4.7.942
cannot obtain vps version (just re-installed)
amd dual core, 2gb ram
broadband internet
web based email
vista basic software (firewall, defender), also adaware

the problem -

had avast pro i guess during the trial, work perfectly! great software! guess the trial came near its end, no biggie just buy it, so i go and use the liscence key click ok, it does its thing great! windows side bar working perfectly, aol instant messenger working perfectly as well, windows media player working also. no new software, files, or updates were installed outside avast.

turn my computer off for the night go to bed

turn on computer next day:
-windows side bar starts, but the gadgets dont load, gui seems to have failed
-try and launch a video wmp does play it (open task manager view processes try n launch again, wmp launches for about 1second then closes, try and launch it with out loading a video (just clicking shortcut) same thing)
-aim doesnt launch either, same sitchuation as described above for windows media player.

i try restarting, reinstalling aim & wmp still problem

i run system restore to go back 2 days

computer runs normal again, cept avast is still about to expire

long story, short, tried liscense key 2 more times same problems, updated avast tried few more times still problem, uninstalled switched to home instead of pro still problem.

i really like this software!! but this seems to be too much of a problem/headache for me! i hope there is an easy fix, or even a way that i could just use the home version at least and upgrade later

any more specifics that i may not have listed??

thank you ahead of time for your time and efforts!