I had a strange problem with Firefox 3.5.2 and Google Desktop. Searching GDS via double-control, would send Firefox to an URL resembling:
which would redirect to my external IP address, and then fail (because I’m not running a web server).
When I switched from Firefox as my default browser to Internet Explorer, double-control search worked. Furthermore, Firefox would work (i.e. not redirect) if I pasted
into the address bar manually.
I tried disabling add-ons, turning off my proxy.pac file, and starting in safe mode. No joy. However, clearing the cache did fix the problem.