This is on a Windows machine, correct? Is everything working, including the optical drive(s) (i.e. CD/DVD)? I ask because if the PC is using IDE hard/optical drives, there <might possibly> be a conflict. IDE is an 'older' technology; any PC made in the past 3~ish years is probably using SATA. The newer (XP on) Windows versions usually take care of this stuff automagically, much better than in the old (pre-XP) days. DMA = Direct Memroy Access, btw. In a nutshell, it allows devices (hard/optical drives) to transfer data to each other without involving the CPU. Does everything seem to work as before this message appeared? Just to be safe, I'd get an external drive (> $100 anywhere, Wally World, Target, Best Buy) and copy anything you would rather not lose over to it. "If you have a good backup, the server doesn't crash" (or the stupid user doesn't delete a file and want it back).