I got an error "Windows cannot connect to the domain, either becasue domain the domain controller is down or otherwise unavailble, or because your computer account was not found. Pleae try again later. If this message continues to appear, contact your network administrator for assitance." when i tried to log on to one of the domain computer using domain user/admin account.
I fix this by:
delete the computer accound in AD, log onto the PC locally. Switch it out of domain and reboot.
Log on locally, switch it to domain and reboot.
In AD, add the computer account again.
Log on to the PC with domain account.
THis worked great for me.
I got this from http://www.pcreview.co.uk/forums/thread-215071.php