How to troubleshoot SQL "The timeout period elapsed prior to completion of the operation or the server is not responding."
Have you tried polling for dbcc opentran? It could be you have an uncommitted transaction problem occurring on that database. Also, worth checking the collation of the databases is the same, always the first thing to check in a "this one works this one dosent" scenario

http://msdn.microsoft.com/en-us/library/ms182792.aspx