Firefox 0.9 and Lispworks documentation?

I've been using Firebird/Firefox for all my web browsing on windows XP 
for quite some time now.  The only application which keeps me from 
making it my default browser is Lispworks.  I've just tried again on 
updating my Firefox to 0.9, and on accessing the online documentation, I 
get the cerror :

Error: Unrecognized application C:\PROGRA~1\MOZILL~2\FIREFOX.EXE 
registered for .HTM files.
   1 (continue) Use it like Internet Explorer.
   2 Abort editor command.
   3 (abort) Return to event loop.

Type :b for backtrace, :c <option number> to proceed,  or :? for other 
options

CL-USER 1 : 1 >

If I take the first restart, then things 'sort of' work.  By this, I 
mean that my documentation is opened in Firefox.  But, rather than 
re-using the currently open window, a new window is opened.  After a 
short time (I use the documentation a lot!), I have a pile of Firefox 
windows open.

I then go back to having IE as my default browser...

So, is there a way of making Firefox work with the Lispworks 
documentation as I want?

Thanks,
Barry.