This is a strange one.

I have a system with /home on cryptofs, in /etc/cryptotab.
Bootsplash is active and silent (vesafb), RUN_PARALLEL=yes (default).
If i boot normally, the bootsplash becomes verbose, i enter the passphrase for
cryptofs and the bootsplash gets silent again.
shortly after, the bootprocess stops (no disk activity, nothing, just the
rotating dots around the kröte). If i now press F2 or ESC, booting continues fast.

If i comment out the "echo silent > /proc/splash" in boot.crypto, it works fine.
If i remove /etc/cryptotab, it works fine.
If i change "RUN_PARALLEL=no", it works fine.
If i run with "splash=verbose", it works fine.

I have debugged it (with strategically placed "echo ^G" :-) that it apparently
hangs at the end of the 
    eval $(startpar $startopt -M boot)
line 173 of /etc/init.d/boot, a beep after this is only heard after i press ESC.

I think it has something to do with switching to verbose and back to silent and
some ioctl or something after that. This is only a guess.