Try disconnecting one of the hard drives installed, move the BIOS jumper from pins 1 and 2 to pins 2 and 3 and power up the motherboard, that should get the system to the maintenance tab, if so, load the system defaults pressing F9 and save then changes, then power down the motherboard and move the BIOS jumper back to pins 1 and 2.
After that, boot to the BIOS and re-enable RAID on the drive configuration menu of through the advanced tab of the system BIOS. Save the changes again, exit bios, power down the motherboard and add the other hard drive.
Thanks for the reply, in meantime I figure out the problem. I used my LCD tv as a monitor connected with a DVI cable, and I don't know why, but the image what I saw it was a video memory buffer image, not the real one. So I didn't saw the effect of F2 but always that RAID screen appeared. Now everything is working fine, exept that in some cases the pc doesn't boot. If I switch off with the power button and power on again, than it's working. I don't know why.
I am glad to know that this issue was fixed. Concerning the other issue you mention, it might be related to an add in device on the system, probably memory, however I would recommend you to start a new discussion over that other issue