New monitor and login problem

[Paul Smith]

Dear All

Beyond Fedora Core 4, I have a partition with Mandriva 2005.
Meanwhile, my monitor changed to a LCD one, and I did the needed
changes in order to use my new monitor with FC4. However, I cannot
login with Mandriva because of the new monitor. What is the best way
to tell Mandriva the new settings needed by my new monitor? I could
plug back the old monitor... but just wondering whether it can be done
without it.

Thanks in advance,

Paul