I spent the last few days fighting Sql Server 2008 R2 installs. Weird errors like "Could not find the Database Engine startup handle." towards the end of the install. Registry keys being stripped of their permissions. Errors like this when trying to uninstall/repair:

"SQL Server setup media does not support the language of the OS or does not have ENU localized files. Use the matching language-specific SQL Server media or change the OS locale through control panel."

And

"Setup.exe - Bad Image
C:\Program Files\Microsoft SQL Server\100\Setup Bootstrap\SQLServer2008R2\setup.rll is either not designed to run on Windows or it contains an error. Try installing the program again using the original installation media or contact your system administrator or the software vendor for support."

I had downloaded the Sql Server 2008 R2 iso from MSDN and extracted the files using WinZip. For some reason I remembered having trouble in the past with using WinZip to extract ISO's. Well, that's exactly what the problem was. I instead extracted the ISO with WinRar and the installs worked like a champeen. I did a compare of a WinZip and WinRar extracted ISO and found that WinZip Fubars a number of files. Not all of them mind you. Just enough where the install run's but you get crazy results. Here is a compare of one of the files (WinZip on the left, WinRar on the right):

Uh, yeah, not good... Anyways, long story short, WinZip #fail, WinRar #ftw.