I have been seeing these a lot lately and so far they have all seemed to relate to missing or improperly referenced libraries that were used during development of various software. Most often is seems to be caused by a redistributable package not being installed on the computer with the error.
If the error refers to "Dependent Assembly Microsoft.VC80..." then it is Microsoft Visual C v8.0 (a.k.a. MS Visual C++ 2005). These are currently available from the Microsoft site. On those pages, you will also find links to similar downloads like .NET versions, and the VB6 run-times. These can help correct various SideBySide errors.
Sometimes the SideBySide errors are caused by a faulty manifest for the application you are trying to run. If the author incorrectly hard-coded custom paths to these libraries while developing, Windows will look for that specific path, and may produce the error instead for searching for the files in various default places.