Ubuntu 12.04 LTS log-in problem

I’ve upgraded my office PC to 12.04 LTS yesterday and all was well.

Being one of the more ‘over-eager’ adopters of Ubuntu, I went ahead with a “forced” update to 12.04 LTS (LTS updates usually come in only during the ‘point release’ of a new Ubuntu version) and look what it has gotten me: I can’t log-in! 

The machine boots fine but when it gets to the log-in splash screen, I select the correct user and enter the correct password but only flashes a black screen with something written momentarily and then goes back to the log-in screen. It does that so fast I couldn’t see the error it’s putting out or indicating. Ugh!

So far, it looks like I’m not the only one with the problem. Could you help us, please?

Many thanks,