gdm failed to start and terminal doesn't show password prompt

[sunng]

I got this urgent issue that I could not login my desktop. The X started but hangs and I could not see the gdm login box. If I turned to terminal, no password prompt after I typed my user names.

I have no idea about this issue. I'm running fedora 15 and the most recent kernel in @updates. Do you have the same experience with me ? And could you please provide me some advices to find the cause.

Thank you!

Edit
And I found these logs from /var/log/messages
Gdm-simple-slave: WARNING: unable to open session: did not received a reply. ....
Gdm-simple-slave: WARNING: failed to get timed login details: did not received a reply...

[linuxwin2k]

Check you disk space (df -h)
or
disable SElinux