Něco jsem našel zde: http://thewinforums.com/topic/26665-default-browse r-now-a-sham/
ale moc tomu nerozumím.

UPDATE:

After doing a little snooping in the Default Programs, I discovered that InternetShortcut "aka .url" under HKCR was being handled by IE. I went in and changed the first entry under HKCR\.url\ShellEx to have the (Default) entry point to Firefox.exe. I was then able to click on links in MS Word and they opened in Firefox. The odd thing is that after changing this setting back to the way it was before I went f..king around with it, MS Word now still opens links in Firefox!!! So have I learnt anything? It'll have to be after a reboot before I find out. I'll be sure to post back here if it reverts to using IE again. If you don't see another post from me, then it means all is now well in my kingdom - !

Cheers,
tk