@ raab:
Switching back from the RST(e) drivers v11.5/11.6 to the "normal" RST driver iaStor.sys may give you some bad iaStorF residues in the registry. To verify it, open the "Drives" section of the Device Manager > "Driver details" and look, if the iaStorF.sys file is still listed. If yes, don't try to delete the iaStorF.sys from the Windows\System32\Drivers directory. Before you do that, you have to erase the wrong "iaStorF" entries within the registry.