Clicking links in Outlook 2003 prompts to download a .exe file ??

[cuemasterfl]

I'm not sure what went awry here, but whenever I click a http link in Outlook 2003 (mailto: links work fine) it prompts me to download a .exe file. The dialog box pops up, with the name field blank, but the 'type' set to .exe, with no other option.

This only started happening today. Any ideas? I know I don't have a virus as I'm very careful about keeping my system clean.