I've noticed on 10.4.11 that it if catalyst is in the startup items, seems to work ok and boot properly with no blue bars (v4. m67)

It used to be necessary to use my startup script, but it was originally written for 10.3 and didnt seem to work on 10.4 at first - I havent had a chance to re-look at it again...

Will let you know if I make any further progress next week.

Simon