Because of an error in data encryption, this session will now end.

This is the error I've been getting more and more frequently over the past few days, to the point that I can't ignore it because it's happening consistently within 5 minutes of connecting - sometimes within a few seconds. Both the remote and local machines are Windows 7 Pro x64. The remote machine is behind a Linksys RV082, and I'm using UPnP to forward a remote port to the correct local port. This setup had been working fine for several months, and I can't think of any recent relevant changes that might have been made.

Things I've already tried:

• Disabling unnecessary components of the network connection on the remote machine, until only IPv4 and Client for Microsoft Networks remain.
• Disabling TCP large send offload on both the remote and local machines.
• Confirming that the remote machine is not mentioned anywhere in any DMZ settings on the Linksys router.
• Confirming that there are no x509-related registry keys screwing things up (this is the suggested fix for a slightly different error anyway).

These are the only solutions I've been able to find after about an hour of searching, and most of them apply to XP or Server 2003 in any case. If anyone could suggest something else, it would be much appreciated.