How to reset default browser for Dell Support Center

I've had to reinstall the Dell Support Center application in my Inspiron 530 running Vista Ultimate. I was running Firefox Portable from a USB pendrive during the installation. For some unknown reason, the DSC has set this browser as its default browser and when I try to use the Support Center, I get a message saying "Wnidows cannot find G:\FIREFO-1\APP\FIREFOX\FIREFOX.EXE".

I've reinstalled it several times, after removing the pendrive, used CCleaner to clean up the registry, restarted several times, etc and I still get the same message and cannot access anything in the Dell Supp Ctr.

Any help on how to reset the browser it uses?