Back button in reverse invoke dsp page

I have got a .dsp application that works fine on the IS server (4.6)

but when I execute it via an RI server outside the firewall everything works fine EXCEPT the browser Back buttion displays the html source, just like right-click, view source. I have to close down the browser and start again.

I do not think I will be allowed to have the firewall rules relaxed, and as I say everything else works OK, any ideas?

graham moisley