Webpage loading stuck on Internet Explorer 8

Question

Hey,

we notice some strange behaviour on Internet Explorer 8. Sometimes our Page (Intranet) starts loading but is not going to finish completly, the IE8 Loading spinner is running forever and the JavaScript of the page is not executed. HTML / CSS is displaying as it should. We use JavaScript (Prototype) to do some stuff and this is not executed. If you hit reload it works.

On FF / Chrome it works like it should.

So how to debug this one? Im not quite sure if its a JS Problem. (We dont get any errors). Seems to me the IE8 is waiting for some response which is not answered by the server.

JS is fired with Event.observe(document, 'dom:loaded', .....

Thanks for your help!