I recently began having this issue and it was getting pretty annoying. This was with Firefox 18.104.22.168 (most current non beta) on Vista.
It turns out that I had recently allowed Skype to install it’s add-on that highlights phone numbers to ease making calls from your computer using Skype. I came upon the solution in this discussion.
Uninstalling the Skype add-on resolved the issue for me.
Posted under Tech Stuff
This post was written by Marc
on May 28, 2008 at 9:02 am