Timestamp in session.log is different with local machine time.?

[#1]

I'm doing performance test in QVS.

I noticed that Timestamp in session.log is different with local machine time.? Timestamp is about 30minutes late than local machine time.

For example, I visit qvw document from accesspoint in 12:00, but the timestamp is 11:30.

Is this a bug? I use QVS 9 sr6 with windows2003 64bit