Installed 3.2 kernel images - computer hangs/crashes on startup

[Gary <listgj-deb@yahoo.co.uk>]

I installed the 3.2 squeeze-backport kernel packages last night (see 

http://lists.debian.org/debian-user/2012/07/msg02186.html and 

original post 

http://lists.debian.org/debian-user/2012/07/msg02121.html if you're
interested in the "why"). Everything seemed to go ok until I came to 

reboot. After selecting one of the 3.2 kernel options in the grub 

menu, the computer effectively froze, with lines all over the screen. 

So badly I had to pull the plug :( How can I find out where the 

problem is, please?