I have a similar problem. I also recently upgraded from Squeeze to Wheezy but when I apt-get upgrade it always fails on autofs:
[....] Starting automount.../usr/sbin/automount: test mount forbidden or incorrect kernel protocol version, kernel protocol version 5.00 or above required.
failed (no valid automount entries defined.).
invoke-rc.d: initscript autofs, action "start" failed.
dpkg: error processing autofs (--configure):
subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
E: Sub-process /usr/bin/dpkg returned an error code (1)
As with Tony, I'm using the default Stable-i386 kernel:
# uname -r
Can anyone confirm that switching Kernel will fix this? Which version should I switch to, I don't need any special functionality, just security and stability.