Have you ever had problems installing CLR samples or the Storefront sample because you get an error like the one below?

Msg 15208, Level 16, State 1, Line 1
The certificate, asymmetric key, or private key file does not exist or has invalid format.

If so you might want to check out the Samples FAQ at http://www.codeplex.com/SqlServerSamples/Wiki/View.aspx?title=HowToUseCodePlex