Um......I had this "freeze" crap myself and it wasn't avast its a real pain is the a44 though.
I open IE and my computer would freeze or be so slow it might as well be frozen.OR yahoo or allmost anything
Try going to SUN and get Java from them, disable VM in internet opitions and try start, acc.,system tools,system inf., and internet repair tool in tools. If not......you going to have to format.........I know I could be wrong but, this could be related to Yahoo freeze boot.........Thats my 2 cents, thanks