Ubuntu Installation :: Can't Boot Clean Install Of 9.10?

few months back I did a clean install of 9.10 from 9.04 (wanted to clear room so decided against upgrade path) and since then I've been really struggling to boot into it. I've used Ubuntu since 7.04 and never had any issues with it - these issues have only started happening since my upgrade to 9.10. And I was hoping that 9.10 would be the release I could persuade her indoors to not boot into Windows XP!

Anyway my problem is that when I choose Ubuntu 9.10 from the boot list it gets to the point where the Ubuntu symbol is splashed up (with the brown background and the light shining on it) and then the little progress bar underneath freezes and the whole box freezes. It doesn't respond to any keypresses like the "magic" ones and I have mashed CTRL ALT F1 plus others keys repeatedly. Caps lock doesn't respond either so looks like completely frozen, though worth noting that the hard drive still sounds like it's spinning.

I've tried with every boot command under the sun (noapci, nosplash, quiet, noapic etc.) and none of them make any difference bar two - apci=noirq starts the desktop occasionally but with no windows manager, and irqpoll stops the freeze but it never loads the desktop or manager. Both these last two commands work about 1 in 10 boots or so but usually it freezes. I can also sometimes press Escape as soon as the Ubuntu symbol shows on screen and sometimes (about 1 in 5 tries) it gets into the desktop, but only if I hit it before it freezes up. The above does point to an IRQ issue but wondering what has changed since 8.10 and 9.04 which worked perfectly?

I've also booted into recovery mode and updated/fixed packages but the same thing happens with the recent 2.6.31-19 generic as well as -17, -14 etc. As per above I'm dual booting with Windows XP as the default boot option (wife's orders) but don't think this is related.