Thanks. Stupid of me, should have Googled!
I found:
"How old is the PC? Does it support ACPI? Even if it does, I've found it to be a bit variable - I have one PC which will run with ACPI enabled under some distros (Ubuntu, Knopix - both Debian based) but not under Mandrake or SuSE (haven't tried Fedora on that one).
Try adding acpi=off to the kernel boot parameters and see if it boots OK."
"RSDP: Root System Description Pointer"
"what you can do is press f6 then f3 then live acpi=off"
I will give it a try, if it fails will post up the other info asked for.
Thanks again for the suggestion.