Well, I had the exact same problem when for the first time tried to install 5.8 SOHO yesterday. I was going to fall back to 5.8 Standard but with the last desperate attempt problem was completely eliminated: I somewhat randomly changed some bios settings and -voila! What I think that did the trick was changed AGP settings or, perhaps, disabled ACPI in Power Management sections. Its definitely ok now.
I recall this issue in a thread recently and adjusting the BIOS ACPI sections (i.e. disabling) solved the problem.