The exception code (c0020043) in the Wireless Lan Problem Report (post #5) points to a RPC_NT_INTERNAL_ERROR.
This is usually set by default, but check Remote Procedure Calls in Services:
Type services into the start menu search box and click on the one that has the gear type icon next to it.
Scroll down to Remote Procedure Call, the status should say started. The second, Remote Procedure Call Locator should say Manual.
I have 2 computers that have the exact same Windows 7 Ult install.
But, how similar are the two after that?
Do you have any third-party apps on this one that the other does not, if so, are they up to date?
Are they connected to the same router?
Are the hardware drivers used to gain access to the net up to date?
Can you tell if this one may have any factors that may cause interference to the router?
Are the Power Options the same or different?
Have you really been to Mt. Everest?
If nothing stands out, then I would go with your gut, and Ken's suggestion to do the repair install to see if the repair corrects the problem.