The upgrade process from an existing installation of Windows to the public pre-Beta of Windows 8 released at BUILD can alter the data associated with copyright protected content to the point in which it’s rendered unusable.
Microsoft has confirmed this problem, indicating that early adopters testing Windows 8 Developer Preview Build 8102 Milestone 3 (M3) can be impacted.
Windows 8 Upgrades May Render Some DRM-Protected Content Unusable - Softpedia