Site Collections become read only Intermittently for brief periods

We have had a problem for over a year now where site collections will go read only for anywhere from a few seconds to several minutes Intermittently.

A user will report that they cannot make any changes, and usually before we can even check the read only status of the site collection, it fixes itself.

In one case I was editing a list in datasheet view, and when I looked up at the scree after editing several rows, the first 3 were fine, the next 4 said I had insufficient permissions, and the rest were fine.  I went back to those 4 rows and was able to edit them the second time.

This seems to occur all throughout the day, and can happen on any of our site collections.

It only happens about once a month the read only mode lasts long enough to get to Central Administration to change it back.

I have noticed that there are a couple timer jobs with content DB locks on them that run very frequently(SchedulingApproval.SchedulingUnpublish ).

Could these be holding the locks on the databases long enough for a user to detect it?

Has anyone else run across this issue?

We are running SharePoint 2010 Enterprise

Thank you,

Kevin