I am on an iMac, OSX 10.6.8, Safari 5.1.2 (6534.52.7).
Next time it happens I will post it here. I am ashamed to admit that I don't know if it was actually UC or LC - pretty unobservant of me.
Edit: Just now:
http://www.gayheaven.org/showthread.php?p=993048#post993048
The result after dragging to my window: http-://oron.com/lv3j7dlg7rox
Interestingly, when I dragged it back
here from my window, it became a ":" again, but when I dragged it back to the
navigation bar in Firefox it became the actual link (no longer the URL itself), which is the usual behavior. Before when the conversion to "-" occurred, dragging it to Firefox failed - nothing ended up in the nav bar - which is when I looked for the problem that I found was the character switch. When I edited it on my window to change to ":" and then dragged to Firefox, it converted correctly to the link.