I have an IPSEC VPN that has worked just fine.. until now...

I am using Cisco client to connect to the ASA 5520 here, I've had success using this setup in the past. In fact just yesterday I was able to connect clients to this VPN....

Setting up a new machine, I am now getting this error on the client:
"Secure VPN connection terminated by the client. Reason 412: The remote peer is no longer responding"

The ASA log is showing an error:
""received encrypted Oakley informational packet with invalid payloads" after several instances of "P1 retransmit package dispatched to MM FSM" and ""Dulpicate Phase 1 packet detected. Retransmitting last packet".

Any guidance on this?

Have more traffic on this from my troubleshooting, will provide soonest

troubleshooting and debugs have narrowed this down to a Max simultaneous login problem. I believe someone may have made some changes without my knowledge...

pardon, ttsaon?

OK I am pretty sure the initial problem was caused by poor connectivity to our Aircard provider. That's been addressed, and now I am getting the following:
error on client: "Secure VPN connection terminated by peer. Reason 433: (Reason not specified by peer)" Which is utterly useless...

ASDM log shows me:
"login authentication failed due to max simulataneous-login restriction"

Testing on a known-good machine and configuration of VPN client (I used it just last Thursday afternoon), I get the same error.

How about some debugs from the box?

Which would you like? I'll have to sterilize them of course...