MOSS 2007 Enterprise again, throwing the above error. I have a custom page
in _layouts that calls a custom DLL that has been working flawlessly (you
know -- more or less).

I installed a new build, the installer GAC-ed it as usual, and I changed the
version in web.config (changed it back just to be sure and got THAT
error)... but even though everything is where it's supposed to be, the error
above persists. I've done some googling and tried things like removing the
xmlns attribute where it shows up in web.config, but no change.

To my knowledge, nothing earth-shattering has changed in this assembly. I
just altered a method to call several other methods under certain conditions
-- methods that were already in use.

Any clues? Nothing's shaking loose here.