Mystery restrictions on opening links

Hi- Would really appreciate some help on his irritating problem: Windows XP Pro, default browser Firefox 3.0.10, secondary browser IE 8,; Outlook 2003; I have administrative rights (However, I do use DropMyRights for Internet-facing programs). When I click on a link in browsers, Outlook or other Aps I get refusal of action messages: "Unable to locate web browser for requested URL"–Firfox "This operation has been cancelled due to restrictions in effect on this computer. Please contact your system administrator"–Outlook. "Update restrictions on computer." –Secunia (program update application). This problem just recently started (not too long after I updated IE with v.8 ) I have tried the advice given in an earlier posting on tghe forum thread (Folder options>file types> edit URL:HyperText Transfer Protocol to "C:\PROGRAM FILES\INTERNET EXPLORER\iexplore.exe" -nohome . But the same problem still is there. Thanks for any help you can give me. Bill

Have you eliminated Zone Alarm as a possible source of the problem by disabling-it and trying ?

Thanks for your post. I don't think Zone Alarm was the problem, but it often is when there are refusal problems. But I've had Zone Alarm Pro for years and this problem had never cropped up before. In any case, the problem seems to have corrected itself because I now can click on links in Outlook, Firefox and other aps and they take me directly to the site. Or, I may have corrected the problem when I noticed that Firefox was no longer checked as my default browser (as it had been for several years). Something happened that left me with no default browser. Thanks again