Error found in Event Log

I have a stack of issues found by the event log for our network. My office is currently upgrading systems from Windows XP to Windows 7. Due to security requirements, we do not have any internet access to a section of our office, and security to that portion of the office is tight. We are required to keep the systems back there up to code with certain guidelines.
That being said, I need to figure out this error:
corruption was detected in the log for the microsoft-windows-grouppolicy/operational channel and some data was erased

I have a lot of similar issues with the systems that need resolved as per our security policy, and I'm thinking that this is a direct result of the upgrade from some of our systems to Windows 7.
Any thoughts?

We have our GP configured to specific standards that can not be changed as per company policy. If it is a setting in GP, then we may be able to get permission to change it, but we do have GP set up, as we did on our XP systems, and didn't have this error.

Thank you for your response and help. I'm glad that this is getting views.

Ok. Thank you anyway.