Clicking the link does an ajax post. There is no visible response in the test case, but there should be no javascript error either. All this works fine in firefox.

In internet explorer 7 and 8, and jquery 1.4.2, the post will fail with a jQuery exception.
The exception occurs when it tries to create an XMLHTTPObject.

Usually if you force a reload of the page, by holding SHIFT+refresh, oddly, the link will then work.

Then go to the address bar, and hit enter so its basically using a cached copy, and the link will fail again.

This is an odd problem, and I dont know how to describe it, but the reload issue is not actually cache related that I can tell. Disabling the browser cache completely produces the same results.

Reverting to jquery 1.2.6 resolves the problem (although there might be later versions which work too)