Has any one seen this behavior before?

While on the IIS server I execute the simple HelloWorldService.asmx web
service directly via the IE browser and it brings up the operation test
page with the supported function as expected.  The Service Descrption
link works fine.  When I click on the HelloWorld test link I get
prompted for a query string as expected.  The probelm comes when I
press the Invoke button.

It should echo on a new screen the XML formated string I typed in
previously.  But IE just hangs there as if wating for a response...
forever.  At this point, I can do a "view source" even though the
browser is still wating for a response.  I get back a properly formated
empty HTML doc with body tags and all.

Here's the kicker,  if I  press refresh on the browser, I get the
proper results shown in the window!

Can anyone help?  I'm sure is a simple setting someware that I don't
know of yet.

Thanks in advance!

Derek