A customer contacted our setup team this week with a problem on their Media Center system - they saw some problems with Media Center, and then tried to reinstall Update Rollup 2 to fix it but then were unable to run Media Center at all because it crashed when trying to launch.
I investigated this system and found that they had a Sony XPS-XL1 system that came with a DVD changer and had a Media Center add-in called Sony Changer that was installed. This Sony Changer application was incorrectly installing a copy of a Media Center binary (Microsoft.MediaCenter.dll) to the system, which then caused Update Rollup 2 setup to fail when the customer re-ran it. I previously described this scenario in more detail in this blog post if you are interested. The bottom line is, with this incorrectly authored Sony Changer setup package installed, any Media Center hotfix that needs to update the file Microsoft.MediaCenter.dll will fail to install and leave the system in a state where Media Center will crash during attempts to launch it.
After talking to some folks on our team and at Sony, I found out that Sony released an update to their Sony Changer application on March 14, 2006 that addresses this problem (as well as some other issues). You can find a link to the setup package for the updated Sony Changer software at this link on the Sony website.
If any of you have bought a Sony Media Center system and have the Sony Changer application installed, I strongly encourage you to install this updated package if you haven't already. We have not yet published any hotfixes after Update Rollup 2 that contain updates to Microsoft.MediaCenter.dll, but there is always the chance that we'll have to update it in the future, and if you do not update your Sony Changer application, future hotfixes for Media Center might fail to install and leave your system in a broken state.