I guess you have the same problems as me...
www.everythingtreo.com/forum/treo-650/help-blazer-cant-open-pages-after-1-20-upgrade-4437.html
So after no one here could suggest anything I fiddled with the settings and realised that with 1.20 upgrade the Proxy setting is enabled....now my Unlocked GSM doesn't use one so I unticked it
(go to Blazer / Options /Preferences / Advanced/ Set Proxy than ensure nothing is ticked)
Hope it helps