I can't replicate this - your code works as expected for me. I don't see the .font.cache-1 file being created either, though, which makes me think that this might be system-specific.

What Solaris version (uname -r) and Tk version (perl -MTk -e 'print $Tk::VERSION, "\n"') are you running?

What happens if you put text into the label when you create it, out of interest?