I have a pavilion 7865 I'm battling with. I had Ubuntu installed on it, but I need to install XP on it. Now, I had XP on it previously and was dual booting, then I wiped the disk and put Ubuntu on it. So I know there's no HCL problem. I loaded 98 SE because all I have (legally) is an upgrade disc. I upgrade to XP, get to "Windows is starting" and get the 0x7b error. It does not state "Inaccessible Boot Device" as I've read when researching it. In Device Manager I have the following problems (yellow ?):
PCI Communications Device
PCI Input Controller
PCI Multimedia Audio Codec
PCI Network Controller

I had a ? by the PCI Ethernet Controller but fixed that.
So, from what I've read the problem was a miniport driver issue.
I installed a miniport driver for the chipset (VIA KT133 ).
I installed the chipset drivers.
I updated the BIOS.
I have searched in vain for a Network and Input controller, which I think is the problem. I thought they would be included in the chipset driver update. Does anyone have any other ideas on what the problem might be? Oh, and wiping the disk and doing a clean install does not help. Sorry about the lengthy post, thanks for reading it.

http://support.microsoft.com/kb/316401

How to troubleshoot problems during installation when you upgrade from Windows 98 or Windows Millennium Edition to Windows XP

These links may help.There are other links attached.

Sourced from Microsoft.