Oracle 11.2g Time Drift problems in alert log and trace files.

If you get a lot of these in alert log:
Time drift detected. Please check VKTM trace file for more details.

And <instance_name>_vktm_*.trc files are growing really fast in trace folder. You have probably hit
Bug 9843304 .

NOTE! You can get this lines in alert log sometimes if your servers clock are drifting (may happen for example in vmware). And that is normal. But if you get this all the time (several days) and a lot then it is probably because of this bug.

To fix this bug install patch 9843304 (You can get it from the MOS (My Oracle Support)).
And after that you can disable those debugging info that are added in logs.
Run following from the sqlplus (and restart database after that):
alter system set event="10795 trace name context forever, level 2" scope=spfile;

Read more from MOS document:
VKTM Trace Files Generated With KSTMCHKDRIFT "BACKWARD DRIFT ENDED AT" [ID 1185093.1]