Hi there - I'm just reposting this from my original post on the old Spotify forum at getsatisfaction, because it seemed that several people per month were using the post to solve their troubles :-)
(Solved) - Tip: Cannot log in on android
Thought I'd post this just in case someone found it useful. I replaced my ROM and subsequently had a weird problem logging in to Spotify (premium member).
Using my Spotify (rather than Facebook) login details, I would log in and then get the popup with 'Spotify can use lots of data if you stream music, etc, etc' message with an ok button. Clicking the OK button or using the back button on the phone just closed and re-opened that same popup in an endless loop. And that was that; the main interface never did load.
Anyway turns out that the problem was that I had installed the 'swiftkey x' keyboard app as a part of the new ROM, and that it was adding a space to the end of my username.
Spotify was then not rejecting the login as incorrect, but obviously that trailing space was messing things up.
When I noticed and removed the space - bingo. No problems...
OK seems like a fairly stupid thing not to notice, but I didn't - and wasted some time looking around for a solution. :-)
Hope I can save someone else the trouble. Cheers!