Pidgin Portable launches IE instead of system's default

I know there was a last-year thread about this, but I can't get around it:

I have set my XP default browser to Firefox portable using the DefaultBrowser utility. For example, at the Windows Run dialog, entering "http://www.google.com" opens a new tab in FF Portable. FF Portable is running (and registered through DefaultBrowser) from a local drive (not usb thumb etc...).

Still, clicking on links in Pidgin Portable's chat windows, IE opens up....

How can I force Pidgin Portable to run system's default browser, or at least set it to run a specific one?

Any help appreciated

have fun,
hypest