Going from the data I guess there is a unicode/1252 translation issue and something to do with a module that was written for a UNIX environment not enjoying the Windows world.

Nope, not a chance

The specifics do not matter - I am more than willing for a few modules to prove incompatible in return for access to the whole CPAN archive.

Cool, lets not speak of them again :)

However, what IS annoying is that any single module that fails to compile stops the whole upgrade progress. Is there any way around this happening?

Sure,

cpan-outdated | xargs cpan -i

cpan-outdated | cpanm

cpan-outdated -p | cpanm

You can also skip tests and force installs, works for install Module , so would probably work for upgrade (not gonna try it)

cpan[2]> force notest upgrade