I'm having this exact same problem in Mandriva Limited Edition 2005. However, it was fine up until I did an update of packages (ie. live update thing or whatever). That's when the problems started. It will not boot into X, just into console, then it will work fine if I type 'startx'. inittab shows a run level of 5, so it SHOULD boot into X but doesn't.
Brief machine description: 2GHz Intel CPU, 512MB RAM, nVideo GeForce 5200FX 128-bit/128MB, 40G and 120G WD Caviar hard drives (linux on 40G drive, WinXP Pro SP2 on 120G drive), WinTV Go, US Robotic 5610B Modem, A-Bit IS-10 Motherboard and I have DSL via motherboard's LAN, SpeedStream modem and a LinkSys 4-port (non-wireless) router. Also have a DVD writer and 3.5" floppy drive. Mouse is a MS optical wheel mouse with a USB to PS/2 adapter and connected into the PS/2 port. I can't think of anything else that would be relevant here.
Here are some of the error codes in /var/log/messages which I was looking at. I removed the date and other numbers to save room here. Just captured the error messages alone:
xfs: xfs startup succeeded
xfs: ignoring font path element /usr/X11R6/lib/X11/fonts/drakfont/Type1 (unreadable)
xfs: ignoring font path element /usr/X11R6/lib/X11/fonts/drakfont/ttf (unreadable)
xfs: ignoring font path element /usr/X11R6/lib/X11/fonts/100dpi:unscaled (unreadable)
dm: Display manager startup succeeded
kdm_config: Unrecognized key 'ServerVTs' in section [General] at /usr/share/config/kdm/kdmrc:78
kdm_config: Unrecognized key 'GreeterPosFixed' in section [X-*-Greeter] at /usr/share/config/kdm/kdmrc:259
kdm_config: Unrecognized key 'GreeterPosX' in section [X-*-Greeter] at /usr/share/config/kdm/kdmrc:260
kdm_config: Unrecognized key 'GreeterPosY' in section [X-*-Greeter] at /usr/share/config/kdm/kdmrc:261
kdm_config: Invalid option value 'All' at /usr/share/config/kdm/kdmrc:293
kdm: X server for display :0 terminated unexpectedly
kdm: :0: IO Error in XOpenDisplay
kdm: Display :0 cannot be opened
kdm: Unable to fire up local display :0; disabling.
The top, I think I know what may cause that, but not sure. And not sure if it would be causing X not to boot. I think more than likely the 2nd and 3rd sets above are the problem. Seems like it's got keys in the config file that are not recognizable? Odd.
Last set it shows that it won't open the display :0 due to an IO Error in XOpenDisplay so it disabled it. THAT is the problem. Display :0 is where X would be put! Something is terminating the display on boot before X can take it over. Just prior to that it did a...
fstab-sync: removed all generated mount points
Now, display :0 can't possibly be a mount point as well, could it?
This does have me stumped. Unfortunately, my other machine is still in the process of being fixed up and upgraded, so Linux isn't installed on it yet. So I'm going to get out of WinXP here and look more into this. I'm hoping to track this error down. I can't promise though...
But since it looks like people with other distros than mine are also having problems, it might be some kind of bug in one of the programs or something that gets updated during a live update and changes one of the config files.