Unable to open the physical file Operating system error 5: "5(failed to retrieve text for this error. Reason: 15105)". (Microsoft SQL Server, Error: 5
Try to attach a database with Management Studio when using Windows 7 and SQLServer 2008 developer edition and one might get an error message similar to the title of the article.
Whether this is a bug or not is beyond my knowledge but the solution/workaround is to connect as SA and not as windows authentication.