PDO SQL Server extension faulting intermittently
There is an updated version that adds support for SQL Server 2012, though I don't know if that will help.
http://www.microsoft.com/download/en/details.aspx?id=17308
Does the non-PDO version of the driver cause the same problems?
This was apparently the result of an incorrect server configuration. Reinstalling the server from scratch and using PHP 5.3.9, Apache 2.2.21 and the sqlsrv driver 2.0 worked with fresh copies of the php.ini and httpd.conf files. I believe I improperly copied some settings from the old server's configuration which caused wonky behavior.