Hi Clifton,
you need to work with the VMware and Windows server administrators on this.
It is not an SAP bug or fault, it is only noticed by the SAP system, and reported in the SAP system log.
When you changed the polling interval to 300 seconds, did you start to see more of these entries in SM21?
My suggestion would be to ask a server and/or VMware admin to check the time synchronization settings for the VMware host(s) and the Windows guests, especially where they get their time data from, with the 'w32tm /query /source' command.
Do they use the same time server(s) as the systems that do not have the problem?
Barring any differences that this may bring to light, and as a definite 'shot in the dark': make sure you are running the latest version of your SAP kernel on your EHP6 systems.
If those servers are otherwise built and configured exactly the same as the servers that do not have the problem, then maybe an older kernel is to blame.
Good luck!
Ruben