Rapid Release Update Error

Hi,

I regularly receive following error:

Server XXXXX was not able to receive Rapid Release Virus Definition update due to an unknown failure.  Check Event Log for details.

BUT when checking eventlog I notice that 3/4 seconds later there is a entry that update was successful.

We have here an SBS2012 installed in Hyper-V. We are using Symantec Mail Security for Exchange 7.0.1.66. It is a trial-version.

RAM must not be the problem (32GB for SBS).

Any Idea?