Tom Warren from Neowin warns us that Windows 7 Beta (Build 7000) has an issue where Windows Media Player 12 corrupts the first few seconds of MP3 files when it tries to download additional metadata about the file (which is the default setting).
"The problem only happens when you edit metadata on a certain class of MP3 file (a file with a header larger than 16KB). When the new metadata is written, it corrupts the beginning of the file. This can happen either when you edit the metadata from inside WMP or Explorer, or it can happen if you have WMP set to automatically fill in missing metadata using the online service and add the MP3 to your library. This problem is only present in the recently leaked build" according to one poster in our forums.
Microsoft's official response is "Microsoft is aware of this issue and it will be addressed in the beta program". Microsoft is currently readying QFE (quick engineering fix) that will be distributed by Windows Update for those with official and non-official access.
Personally, I think it’s great that MS will put out a patch that will work with the build that leaked. I wonder how the bug creeped into the build in the first place. Well, I would recommend sutting of the metadata lookup in WMP12 for the time being, whatever build of Windows 7 you may be running.