...ActiveState has removed Perl/Tk from their ppm repository
You should be able to take care of that with:
ppm install http://www.sisyphusion.tk/ppm/Tk.ppd --force
Update: Ooops - essentially repeating advice already provided by marto.
The sisyphusion ppm packages all want to install the same small gcc dll - and many version of PPM won't allow (without --force) the overwriting of a file that was precviously installed by PPM (even if the files are identical).
Hence, installing from that repo usually requires --force.