To mitigate this issue, Security Response is no longer incrementing the date on SEP Security Content and instead only incrementing the revision number of the content.Security Response will continue to provide definitions in this manner as a work around until a permanent solution can be provided.
This issue has no functional impact on the protection technology of the SEP client.
Below is an excerpt from the Symantec Antivirus knowledgebase, Symantec antivirus, although it updates the same as before, doesn't recognize a date newer than 2009.
The fix: release new definition updates, but keep the December 31, 2009 date.
You may need to download and run a cleanup utility for your previous security application in order for it to be completely removed.
Caution When you remove Internet security programs, your computer is unprotected.