I have the same problem. VM console runs for 11 days, and on the twelfth day of the console stops working. During the connection get the error: Unable to connect to the MKS: Malformed response from server.

Helps only restart the host.

ESXi: HP Custom ISO 5.5.0 1331820

VC: 5.5.0 1312298

Have any ideas how to solve this problem?