Not very recently, bryn. But I think I did it not too long ago, probably only a few weeks ago while trying to fix an HTTP 400 Bad Request error I keep getting. I think this started around that time.
The strange thing is, I'm running IE with the add ons disabled, but when I went into Manage Add-ons right now, there were a bunch that were still enabled... I mean a BUNCH.
Any way, its not happening right now and I disabled some, so I'll let you know if anything changes.
EDIT: Okay... so, its weird. Its still not happening yet, entirely. I was poking around and on dA (which is where I normally do a lot of tabs), I opened a picture that was a broken image thing - y'know, gray box... white square, red X? Well, when I tab that and click on the image to view it at full size, then close it... the error pops up.
But its not doing it on any other tab - yet.
Okay, so.. cleared my TIFs (temporary internet files) and cookies. We shall see if that does anything. It fixed the broken image on dA.
Strike that. Pointless move. Actually seemed to cause it. Went to dA, opened a few tabs. Closed one. It froze a second, then closed on its own. Closed another, it froze and the "Do you want to fix or close" options. Closed a third, and it closed fine.
Could it just be happening because I'm opening too many tabs? I dont open any more than 4 or 5 at one time...
EDIT 2: Okay, its happening again. Now its happening with every tab. Hit "Find solution and close" with all of them, didnt change anything.
Went back and used IE with out the add-ons. It stopped, the problem is is that when I look at the addons, nothing has changed. The addons that were enabled before are still enabled. The ones that were disabled before are still disabled. I just went through and disabled everything, so we'll see...