About 2 weeks ago, I started getting the following error from my TZ210W:

"The cache is full; 399 open connections; some will be dropped"

The source is always a computer on my LAN or WAN and the destination varies. I get this error about 20-30 times per day. 

At the time this started, there were no changes to any device on the network, except for maybe an automated Windows update.

I pay for support and have been in touch with Sonicwall support, but they've been less than helpful and have stopped responding to my emails. They seem clueless.

Any suggestions on how to figure out why the cache is filling constantly would be appreciated!

Background info: There are only 2 users on the network and there is a Web Server in the DMZ. There are also wireless devices connected to the WAN, but the errors have almost always been from the 2 desktop computers. I have "Trend Micro Maximum Security" running on all of the computers on the network and have performed detailed virus scans with no issues. I also have Sonicwall gateway antivirus running on the router.