[Project_owners] extension stops working under Firefox 3.0.4 -- please help

[can]

Many thanks again to all the nice people who helped me with my first 
uninformed question.  I think this one is a little more substantive.

I have written my first "Hello World" Firefox extension.  I had some 
confusion about installing it, but I think I got that straightened out now - 
BUT ONLY under Firefox 3.0.3.  Yesterday, Firefox updated itself without 
giving me any chance to stop it (at least as far as I could tell).  I now 
have version 3.0.4.  I didn't think that would be a big deal until I got 
back to trying to work on my extension.  Now, the exact same extension that 
works under 3.0.3 will not install under 3.0.4.

I have tried two install methods: (a) copy my extension directory to the 
Firefox profile/extensions directory (where Firefox installs), (b) set the 
appropriate Windows Registry key to point to a directory where I have 
unpacked the contents of my .xpi file.  In case (a), Firefox starts and I 
see *nothing* new in the Extensions window.  In case (b), Firefox starts, 
and I see an entry for my extension, but it is whited out and there is a 
message that says, "This extension is not compatible with Firefox 3.0.4."

I have a separate computer that (thank God), is still running 3.0.3, and 
everything still seems to work there.  I tried searching for posts from 
other people who might have encountered this problem and have come up with 
nothing.  Can anyone help?


As a related question, hopefully much easier, can someone please tell me how 
to stop Firefox from updating its version WITHOUT my permission?  I would 
expect at least an OK/Cancel box.


Thanks,
can