[MT-AU Public] PPTP routes

Hi all, have router A (962UiGS-5HacT2HnT) (6.34.3) and Router B (RB951G-2Hnd) (6.35). Router B dials router A over PPTP and I added routes so B network can access A network, it all works. Problem occurs once router A reboots, it loses the static route gateway and says it is "Undefined" which then means network B cannot communicate. Selecting the dropdown box and choosing the PPTP connection (gateway) gets it all going again. If Router B reboots, the problem does not occur. I understand that the PPTP connection has disappeared which is why the gateway also goes but it seems this would be a reasonably frequent problem and should not occur. any ideas on a soulution? thanks -Matt