Thanks for the speedy reply to my post.
However I believe that you may have misinterpretted what I was stating. It's not Avast that wasn't starting up. It's Windows itself.
I turned the system on this morning (It's half past noon atm where I am), updated Avast, and rebooted, and that's when Windows would freeze on restart. I never actually made it to my user login screen. My computer's never had this issue before and I've been using Avast for the last, well I'm not entirely sure but I'll say 6 months, without major issue.
Furthermore I had been refering to Last Good Configuration, not Windows System Restore, as W2k does not include said functionality.