I've been bit by this at work recently, and I thought I'd try to figure out what the problem is.

Doing a google on Cut paste broken in Firefox will give you 288,000 results. Seems like there could be a problem there.

I even found a site (can't find the link now of course) which had some very elaborate steps including going into .js files within your profile directory and modifying values.

Well, I think a simple solution has come about for this. See, I have 2 monitors at work and I have to admit, I only have this problem at work.

A co-worker suggested that maybe it was because I was cut/copying in one monitor and then trying to paste in the other monitor.

Hmm....

So I I drag the window I want to paste to over to the other monitor, and try a Ctrl-V. Nothing. Well ok, let me go try to do a copy again. Ctrl-C -> Ctrl-V and it works!

The even stranger thing, is that I can copy/cut content from the actual webpage being displayed, its only the address bar that doesn't carry over.

Go figure.