IE toolbar edit button disabled due to compression

Team,

Can't turn up anything in TechNet or Google for the following so
thought I'd ask your esteemed selves.

Intranet setting - IE 6.0.290.2180.xpsp_sp2
When compression (gzip) is enabled on the server side the Internet
Explorer Browser toolbar edit button is disabled.

Pages can still be edited using Edit tool but opening it / file / open
etc, but the Browser button is greyed out.

Browser button is primary edit initation point for most users editing
their content.

Anyone have any suggestions on how to enable the browser button again,
while keeping compression enabled on the intranet ?

Many thanks

Follow up

Problem exists for multiple logons on the same machine
BUT
seems to be only one machine at present

IE 7 and other machines running IE6 don't seem to have the problem.

Any light anyone can shed would still be useful

I've tried uninstalling and reinstalling IE on the box affected - no
change in behaviour.