[Running Win7 Ultimate 64 bit]

My new HP Pavilion Elite HPE-450t has been plagued by BSDO crashes since I got it about 5 weeks ago. The crashes are somewhat rare, sometimes not occurring for 3 or 4 days. I have spent a lot of time trying to isolate the device that could be at fault, but I have seen crashes with only the keyboard and mouse plugged in (as USB devices), and I tried two sets of keyboard/mouse, so I'm running out of ideas. :(

The WhoCrashed tool gave this info about my latest BSOD:

crash dump file: C:\Windows\Minidump\121310-11887-01.dmp
This was probably caused by the following module: usbport.sys (USBPORT+0x2DE4E) 
Bugcheck code: 0xFE (0x5, 0xFFFFFA8008F571A0, 0x80863B34, 0xFFFFFA80092F2510)
Error: BUGCODE_USB_DRIVER
file path: C:\Windows\system32\drivers\usbport.sys
product: Microsoft® Windows® Operating System
company: Microsoft Corporation
description: USB 1.1 & 2.0 Port Driver
Bug check description: This indicates that an error has occurred in a Universal Serial Bus (USB) driver.
The crash took place in a standard Microsoft module. Your system configuration may be incorrect. Possibly this problem is caused by another driver on your system which cannot be identified at this time. 

I looked at http://msdn.microsoft.com/en-us/library/ff560407(VS.85).aspx, and for Parameter1 = 0x5, it says "A hardware failure has occurred due to a bad physical address found in a hardware data structure. This is not due to a driver bug".

Should I conclude that it's a hardware issue in the machine itself, rather than a bad USB driver or USB device?

Here is the MiniDump, in case someone can get more info out of it: http://ewt52q.blu.livefilestore.com/y1peS4Ce8nSK1SXghzMDoxDWXlaEu-EKCJsv25y8y5DXXIUzZ9U0_tYgFJXd939fykwa0zRmx98IW0PYG18GioqKAuARYjtspSA/121310-11887-01.dmp?download&psid=2