Have you tried to upgrade the IE browser recently? Also you have not mentioned the version of Office you are using as the solution will depend which version you have. Normally this is caused after you upgrade to a newer version of Microsoft Internet Explorer the following registry key may either missing or corrupted:
HKEY_Local_Machine\Software\Classes\htmlfile\shell\open\command. For eg. if you get this error message when you click on any link in the outlook mail the lets try these steps here below:
If you have Internet Explorer 7 or Internet Explorer 8:
-Start Internet Explorer.
- On the Tools menu, click Internet Options.
- Click the Advanced tab, and then click Reset.
-Click the Programs tab, and then click Set programs.
- Click Set Default Programs.
-Click to select Microsoft Outlook, and then click Set this program as default.
- Click OK, and then close the Default Programs dialog box.
-In the Internet Options dialog box, click the Programs tab, and then click Make default under Default web browser.
Now restart office program and then try to click on the links again.
Here's to Good Karma.