PPTP broken in 10.4.11

We use 10.4.11 to VPN into a Nortel Contivity, this broke recently from some Apple update. it is working fine on 10.4.9. Is there a way to back off the last security update? Anyone else broken with it? we have multiple machines that broke with the update, my personal machine still works but I didn't install the update and won't until we find a fix. thx