All of a sudden (the day after upgrading from SQL Server 2000 to 2005) on a x64 machine, we got:

The server was unable to load the SSL provider library needed to log in; the connection has been closed. SSL is used to encrypt either the login sequence or all communications, depanding on how the administrator has configured the server. see error message 0x2746.

Judging from other forums, it might be due to a temporary resource peak at the server. Anyone having any other theories?