10.5.6v1.1 - can't Login

Hello,
I have updated to Leopard Server 10.5.6v1.1 thing is when I reboot the Login Screen is just showing up as Fuzzy! I can't see where I should be able to enter my User Name and Password so can't login, can someone please help me with this, most of the screen is Blue and the top half is all fuzzy. below are the specs of the Mac I am using, I also have a MacBook and updated to Leopard (Non Server Edition) 10.5.6v1.1 without any issues.

Mac Pro, 2x3.2Ghz Quad Core Intel Xeon, 16 GB RAM, 4x1TB HD, 1.5GB Nvidia Quadro FX5600 Graphics. Was running Leopard Server 10.5.5 up until now no bother.

Just to note that I have 2 External Drives (Firewire) and I have all of my personal data backed up, I also physically removed my startup disc and installed a Fresh copy of Leopard Server and ran the Automatic Apple Update and I still have the same issues.

The thing is that I purchased iLife 09 and can't use it now due to these issues.
Many thanks for reading this hope someone can help. I have attached a photo of the Login Screen where my system does not allow me to login at all.
Regards,
Colin.

Well it's been a long time going with this issue since January 2009, anyhow since then I have been in touch with the Forums scanning for info also been speaking to 4 apple Techs, friends etc, until tonight I just sat down and made a complete list of all the above supposed fixes, none of them worked! out of pure luck I fiddled around with the display connector at the back going into the Mac and it seems like it worked! I can now reboot into 10.5.6 actually I have installed Snow Leopard now and had the same issues but when I remove the display connection and plug it back in everything works fine! only thing is when I restart or shut down and go to login again the screen is all fuzzy so everytime I now have to reboot I have to disconnect and reconnect the DVI cable! talk about a pain in the back! I think it could be an issue with the graphics card now. am getting a free replacement to try it out so will know soon enough!

Those pictures are definitely graphics related, whether drivers, card failure or bad connection.