TrueMobile2300 and Windows Update

Every time I try to access Windows Update I get the following error in one, two, or three places at the top of the 3 frames on that site:

Bad Request (Invalid Verb)

Windows update just will not work.  If I connect my computer directly to my cable modem and bypass the true mobile 2300, the windows update works like a champ every time.

Until I had turned off the router for a length of time a few weeks ago, I was having a lot of trouble with .asp links.  I know Windows Update uses .asp links to run the page.

Does anyone have any ideas why the router (I assume/guess it is some sort of NAT problem in the router) is doing this?  The only NAT type settings I have active restrict the websites one other computer on my network can access (but the windows update is allowed on that computer).

Thanks for any thoughts.