I have just built a media center PC for myself and am having weird 'freezes' - I have also seen this in other PCs that I have installed with nVidia chipsets/AMD CPUs.
Basically what happens is the PC runs fine then at seemingly random points, it appears to 'freeze' where I can move the mouse around and even bring the Start menu up but nothing else. The hard drive activity light goes solid and nothing responds for between 30 seconds and 2 minutes (I haven't timed it exactly), then all of a sudden, it comes back to life and carries on fine, until a few minutes later, it does it again, ad infinitum. This is a fresh install of Vista Ultimate with the very latest nVidia chipset drivers and graphics card drivers. There isn't a BIOS update available. Like I said above, I have seen this before with nvidia chipsets on other people's PCs.
AMD Athlon64 4000 Socket 939
ASRock 939N68PV-GLAN motherboard with a nVidia nforce 630a chipset with the latest 14.10 drivers
ATi Radeon HD2400 graphics card with 8.3 drivers
Samsung Spinpoint 250GB SATA HDD
I don't think you need to know any other details, but I can provide them if you want.
Any input/help would be appreciated as this problem renders the Media Center side of things un-usable as the TV keeps 'freezing'
Well, I kinda figured it out. It's the SATA controller driver (nvstor32) that keeps 'resetting' - From what others have said, disabling the NCQ or 'command queuing' option in the driver properties fixes it, but it didn't for me. I'm gonna try reverting back to the driver Vista installed to see if that sorts it, altho it'll probably run slower. Oh well.