Strange Gnome behaviour

[huw]

Hello all

Yesterday I upgraded Edgy to Feisty using Ubuntu's built-in automatic 
updater.  It appeared to go well but I'm now having problems in Gnome.

The worst problem is the left mouse button (LMB) doesn't work properly 
unless I hold down the control key.  If I don't, the LMB appears to do 
nothing when clicked, but if clicked and dragged will draw out the 
expected selection box with the odd side effect that whatever is within 
the box will be saved as a screenshot on my desktop when I stop pressing 
the button.

The other major problem is none of my windows have title bars.  I think 
this may be related to my nVidia drivers from what little I've managed 
to read on message boards so far, but I haven't yet seen anyone come up 
with a solution.  Web browsing is quite a pain at the moment as you can 
imagine, so I'm not checking very often.

I will gladly post whatever info required to help me solve this.  One 
last clue - this only happens for my user account.  There are two other 
users on this PC and they have no problems (including the title bar thing).

Any help gratefully received!

Huw