In the message catalog of gdm, a lot of messages occur that are in the
"I-form", like:

"I cannot start the X server (your graphical interface).  It is likely that "
"it is not set up correctly.  You will need to log in on a console and rerun "
"the X configuration program.  Then restart GDM."

Other GNOME software doesn't refer to itself as "I" and I feel it is bad
style to anthropomorphize the computer (though I can't support this with a
style guide recommendation or anything like that).

The second problem visible in the above message is the mentioning of "GDM".
The user is very unlikely to know what GDM is. "the GNOME display manager"
would be better, though still a bit vague to the uninitiated...