What version of TextMate? The Language Definition bundle was renamed to TextMate in September 2005 [1].
Oh. 1.5.4.
It all seems to be working now, so I've stopped worrying. I do find the Bundle update behaviour wierd, but that's just my brain.
Steve, my fresh install consisted of a new download and deleted prefs, rather than a whole new account, but as I said, finding and dragging the Textmate bundle from Pristine Copy to Bundles did the trick.
Bruno