SupportAssist Enterprise 4.00.06 for VMWare ESX stopping services

Every couple of weeks we get errors that SupportAssist isn't able to verify the connections to Internet, SMTP, Enterprise Servers and Global Access Servers. The funny part is that we receive this by mail, so SMTP is working.

When logging in to the SupportAssist interface and running the Network Connectivity Test, it is succesful if only Internet Connection or SMTP server is selected. The Global and enterprise servers test fails.

Looking under Admin > Service Status there are the following errors:

Restful Service
We have encountered a rest service error. Try again later.

Core Service
We have encountered core service errors. Try again later.

Behind OpenManage Enterprise there is a status that shows a red circle with a cross.

Restarting the appliance fixes the problem for a while, but it keeps coming back.

Is someone else having this issue or where can we start looking to solve this problem?