I set up a Centos 5 machine a couple of weeks ago and everything was working perfectly. It survived a few reboots and whatnot with no problem.
I moved it to another location on Saturday afternoon and, again, it booted up and worked fine.
It was rebooted this morning and now the graphical login screen doesn't appear. Everything appears to load normally but once the text login screen appears, that's it. No graphical login screen.
If I log in at the text console and type startx I am told that X is already running.
If I hit ctrl-alt-f7 at the text login screen I see a completely blank/black screen. If I then hit ctrl-alt-esc the graphical login screen comes up and everything works as it should.
If I switch to runlevel 3 and log into the text console and type startx, my desktop shows up just as it should.
There are no errors that I can see in /var/log/Xorg.0.log.
Again, this all worked fine up until this morning and nothing changed. Today I rebooted it several times and I consistently get the behaviour detailed here.
So, what could be going wrong and preventing the graphical login screen from loading?