Browser hanging, slow loading, etc.

I've recently been cleared through MG's Malware forum, but still have an issue with my Browser hanging or not loading sites. It is worse at times than others... not sure why... I feel like something is missing (a registry code?) because it acts like it cannot move from one site to the next properly. For instance, if I respond to a question in Yahoo Groups, the browser (IE or FF) will appear to be "spinning its wheels" but often, when I return to the messages, my response is there. Any ideas? Thanks.
-pjubber
Windows Vista
Firefox and IE 9
Defender
Avast
CCleaner (daily+)
Spyware Blaster