Ok, i think my machine has been compromised.

Its NIC and HDD light randomly go in the night
Its slow and Wierd errors occur
Free HDD space mysteriously fluxuates
Avg and Windows Defender randomly close themselves
Ctrl-Alt-Del is kinda screwed up
Sometimes i have "insufficent permissions"

luckily this machine isnt on my LAN (it has its own by the minute dialup rather than be connected through my broadband router) - long story dont ask.............

Repartition, Reformat and Reinstall?

Yes, I think its the only thing which will give you peace of mind...will help you in pinpointing the exact cause of error( hardware or software ).

well, ive also noticed something or someone has been playing with my regisrty.

Im gonna clean reinstall NT