Amilo pi2550 drivers

I have a Fujitsu Siemens amilo pi2550 and I think there is lack of some drivers.
Grub is loading perfectly, but when it's time to boot ubuntu it cannot find the hard drive. It looks like it's searching but cannot find it.

I read somewhere to set in the /etc/default/grub file "processor.max_cstate=1" and then update my grub. If I do this in the next reboot everything works fine. But I suppose that's not a really good solution of the problem cause the processor is runs always with max power, even if it's not being usedfo some time(I'm not sure about that).

So because everything is solved with the "processor.max_cstate=1" thing, the only fact I can think of is that it's some lack of drivers.

P.S. Sorry for my bad english.
P.S.2 I'm quite newbie with linux so I'd appreciate some simple explaining.

thanks in advance