Situation: MacBookPro 6.2 triple boot (rEFIt): snow leopard + W7 + Ubuntu 11.10 (updated from 10.04) everything working fine.

Problem: automatic update of ubuntu 11.10 > reload > grey screen with question mark: no boot at all!!

tentative solutions:
start + opt -> no result
start + D -> no result
start + opt + cmd + P + R -> no result
ubuntu 11.04 live CD + start + C -> OK everything working fine but cannot mount the HDD
original system disk (mac OSX 10.6.3) + start + C -> I can see apple logo and the wheel, but after some minutes everything is frozen

I suppose that something went wrong with rEFIt during the ubuntu 11.10 update, but I do not know how to operate.

Is there someone that can help me????

Thanks a lot for any suggestion