Multiple VPN connections thru Linksys WRT54G

Hey guys. My wife and I both work from home at times (for the same company). One of us can connect fine. But if the other one conncts, one of us will get bounced after a short while. Router is a Linksys WRT54G. VPN client is Cisco 4.8. My gut tells me the router, when NAT’ing our traffic over UDP-500 (or another port) gets to a point where it can’t distinguish between our machines, causing one of the tunnels to drop. Any help and configuration advice would be greatly appreciated.

Del