I have several PCs which SSH into a database server. One Linux PC running Xubuntu 6.06 with openssh-client v1:4.2p1-7ubuntu3.1, which was working perfectly well up to yesterday, suddenly stopped connecting to the server. All the other PCs (including those running Ubuntu 6.06) can still SSH in OK. The faulty PC can still access the internet OK, and I can SSH into the openssh-server on the faulty PC. I just can't SSH out of the faulty PC, either from Gnome Terminal or from the console, either as the usual user, or as the admin user.
Using 'ssh -v' it hangs silently at:-

debug1: Connecting to ... port 22

Then after about 10 minutes it exits with 'Connection timed out'.

I've tried removing openssh-client and openssh-server including config files, then reinstalling - made no difference.
I've tried after disabling the firewall in Firestarter - same.

Can anyone suggest anything else I could try or test?