I don't think the other two posts address the question that you are asking.
I have two customers who have expereinced problems with the Endpoint Agent (DLP 12.0) + IE8 + Monitoring HTTPS.
I've reached out to Symantec and there is nothing officialy listed as a bug in their e-track system. If you do end opening up a case, please let them know there are two more customers expereincing the same problem. IE8 is supported for monitoring so I'm not sure what is happening.
Good luck