We found problem, Similarity doesn't have internal MP3/WMA decoder, it depends on Windows Media SDK, DirectShow, Microsoft Multimedia Foundaition or Apple Quicktime components, Similarity contains only open source decoders (FLAC/APE/WavPack/etc...). Windows Sever 2008 doesn't have pre-installed such technologies as Desktop versions.
You have 3 solutions:
1) Install Apple QuickTime SDK
2) install the "Desktop Experience" feature in Server Manager
3) Also you can manually install Windows Media Services (but this is hard way)
http://support.microsoft.com/kb/934518