That definitely looks like the known issue. The link to the official KB on the subject has been provided above by another forum member.
There are two workaounds at present: use SMB (not SMB2) for the fileshares, or disable NTP. Disabling it just on workstations won't likely help matters.
This issue is expected to be corrected in the next release of SEP. No exact release date is currently available, but it should be within the first part of 2011. It is possible on Symantec's website to subscribe to notifications of new releases for products- highy recommended!
Thanks and best regards,
Mick