Is titanal an aluminum alloy? Too bad about the manitou but cracked is more common than not as you know!
On the Titanal, there's a couple of articles on it out there on the web. But basically it was flat sheet that was rolled & welded along the seam. Then it couldn't be welded, so was attached by lugs. On some frames the welded seam failed & it looked like it exploded from the inside- out.
I have 3 different Manitou F/S frames & 1 Hardtail. All cracked.