Is this with Eudora's internal viewer or the 'Microsoft Viewer'?
With the MS Viewer, links should work as long as the sender has formatted them as links, and not plain text.
I'm not sure whether the internal viewer will render all links correctly now, I don't use it, so I can't say.
Next time you get a message with un-clickable links, right click on it and select 'send to browser'.
It should then open in your default web browser.
Do the links work there? If not, they haven't been formatted as links by the sender.
HTH. Cheers, Dave.