[X4U] Mailto Protocol Won't Register

[Rick Gordon]

[OS 10.3.8]

I have had Eudora registered as my email protocol for a long time. This evening, mailto links from Firefox no longer opened into Eudora (or any other application). I went to reset my mailto protocol using the More Internet preference pane, but it would not accept Eudora as a choice. (Eudora is functioning normally, as far as I can tell.)

I tried setting it both in Internet Explorer and Misfox, but none of the three interfaces would accept setting it to Eudora, although it would accept setting it to other email (and non-email) applications. 

I've tried copying my Eudora application from my laptop, as well as copying the similarly configured com.apple.internetconfig.plist and com.apple.LaunchServices.plist. I've rebooted. Nothing works.

Do you have any suggestions?