Problems with new build and up2date

[Alexander Sharaz]

Chaps,

I've been building a few new RHEL 4.0 servers here and everything has
been working just fine .... until I ran up2date on them a week ago. On 2
boxes I've now had the message "Could not recognise image file format
for /usr/share/gdm/themes/Default/badckground.pns"  at which point
logging on via the console just stops. On 1 system I booted the box off
the cd and accessed the system via the linux recover command. I then
tried changing the symbolic link to point Default to one of the other
themes. Basically at some point I get  the same message when attempting
to access a png file 

So ...

1). Any idea how to fix this problem
2). What do I change to get to a text only console setup

TIA
Alex