If interested this is what happens when you leave a bottom bracket with alloy cups (it was a un-91) in a titanium frame for 13 or 14 years. Pulled this out of my litespeed saturday night (just before the long mynd ride), as you can imagine it was a right twat to get out. Fortunately a combo of a workstand, massive scaffold bar, some GT-85 and WWF-esque effort shifted it. The non drive cup had corroded pretty badly, a fair bit of it was like powder.
The drive side cup was fine, came out no bother. Not quite sure why, would've installed the bracket with grease / copper grease. Perhaps I forgot on the non-drive, didn't put enough on or the fact it's slightly more exposed than the drive caused the issue.
Almost (but not quite) tempted to go an dig my materials text books out the loft to read up on this.
After a quick clean up the b/b shell looked good as new and the NOS UN-71 very kindly supplied by Robert went in no bother