Foxfire 1.0 freezes 20 seconds

Firefox 1.0 (virgin install) freezes on web page clicks and other normal
operations. "Not responding" message when I try to close app.. or if I 
wait, the "hourglass" finally disappears and it continues to work until 
it hangs again. Makes browser unusable. Other apps not affected. No 
connection to load.  Tried Netscape 7.2 same date with similar results. 
Dec 31, 2004 both downloads. My guess is DNS lookup failure as the 
problem improves if I re-request a page. Makes Firefox unusable.

PC: new Intel P4 with HT
OS: Windows XP MCE with SP2, security updates
Connection: broadband connection on home network
Compare: Works great on an old PC/XP Pro, same network, Firefox 
extensions, etc.
Suggestions?