G5 Dual 2Gig with 10.5.6

I have four displays running from the stock 9600XT AGP and a 9200 PCI. These were all working fine in their proper resolution. 3 of the displays run from DVI (1 via Mac connector) with the other running out to VGA.

Just upgraded to 10.5.6 and there seems to be a problem with (any) two of the monitors and not just two from one card - i.e. the problem seems to be one display from each card. When I swap the displays around I get the same problem but on the new monitor.

The problem is that two displays are not recognized and so are given a set or default and wrong resolution. Also the Leopard background pic of the Universe is blue (instead of Black of space).

It can't be a problem with one of the cards as it affects one display from each card and it can't be the displays as when I swap them around the swapped displays get recognized.

I read that 10.5 (upwards) has all the necessary drivers etc etc... so any idea what is wrong??

Thanks