Problems in upgrading in grahical mode of FC4 to FC5

[Joep Blom]

I have the following problem installing FC5. I had installed FC3 en FC4 
so I did an upgrade.
System: AMD64 3000+, 1 GB,disk: 80 GB, DVD-ROM & DVD rewriter. 
Installation from (selfburned) DVD.
Video: card nvidia; LCD monitor :H-freq: 31-81; V-freq. 56-75.
Problems:
   1. When starting installation in graphical mode, screen goes black 
with a small window saying: "signal out of sync".
2. Installation in text mode is completed but X is not installed and 
even the old X libraries are all removed. Therefore graphical mode is 
also not possible any more in FC4 (luckily FC3 still works as it is on 
another partition and I UPGRADED FC4 to FC5).
My questions:
A. Is the problem known and how to solve it.
B. How can I (re) install the X windows system.
Hope anybody can help me out!
Joep