Combo Thunderbird- Firefox link Problem

[walkerpbus]

This only happens on 1 machine, so that makes it suspicious. I've just reinstalled Firefox on that machine, but it happened before the reinstall to my wife. Anyway, ordinarily, you click on a link in a TB message, it opens up a new tab in FF. (However, there's another problem with FF opening up a new tab with Roboform (my password-login program) so maybe I'll copy this to the FF support forum.
Any ideas on this problem? Thanks for any suggestions.

[DanRaisch]

Cross post. Locking. Continued in viewtopic.php?f=38&t=1480235