Debian :: Upgrade From Sarge To Lenny (via Etch) Has Broken Cron?

I've been upgrading a bunch of our servers from sarge to etch and then to lenny, on two of these servers, cron has broken, cronjobs will not run. On another two (that have no significant differences from the others) cron is unaffected I created a simple job to run while I was testing

*/1 * * * * root /usr/local/mailtest-1 in the script is echo test mail from busted server | mail -s "test mail from your busted server" [URL]. and that runs fine if I run it manually, I've added it into /etc/crontab and crontab -e but haven't got a single mail from it. The cron service is running

I tried apt-get remove --purge and then a re-install but it doesn't seem to have worked. All the logs have stopped rotating as well so I'm starting to think that maybe it's not a fault with cron but with some other service that it depends on. However, I've not been able to figure out what that might be.