I had it happen to me a few times, but it's been so sporadic/unexpected as to be hard to pinpoint a reproducer.
I *think* it's because tabs are both "a tab" (the UI thing) and "a file" (the proxy thingie in normal title bars). So when you click one, if you slightly misclick, you can drag the tab "over" the text view. As it is considered "a file" by the text view, TM tries to calculate an insertion point, which races with the grammar/syntax coloring that's going on (remember, you've just brought this tab to the front by click). Then you loose the runloop because something raised inside the modal drag loop, and you have to force quit.
It's fiddly, I might be completely/somewhat wrong, but hopefully this helps — to me it's the only major "crashing" bug I've seen in years of TM usage, and it only happened twice.