We have several old ASP and PHP web applications which use SQL Server Authentication. Periodically, all the applications lose the ability to connect to our SQL Server 2000 database server, getting access denied.

Corresponding to roughly the same times, we are getting

1115 Cannot generate SSPI Context SQLSTATE HY000

errors on the SQLServer 2000 server.

And here's the weird part - rebooting the web server fixes the problem. Rebooting the database server has no effect.

This makes no sense to me - I didn't think SSPI was in any way involved with SQL Server Authentication.

Any ideas?

Edit:

Some additional details:

The web server is in the DMZ. The hosts file on the web server has an entry for the database server (and the ip address is correct), so the web server (theoretically at least) shouldn't even be going to DNS to connect to the database server.

It does not appear to be a firewall issue.