Fix PHP MSSQL sqlsrv problem

I URGENTLY (within 24 hours) need someone to fix a problem i'm having with a PHP MSSQL job, specifically related to the insertion of a GUID from a php script to a MSSQL2008 backend. (INFORMATION ATTACHED here [login to view URL]) sometimes the records will insert without a problem, othertimes, the screen will return the following error: Error in statement execution. Array ( [0] => Array ( [0] => 42000 [SQLSTATE] => 42000 [1] => 8169 [code] => 8169 [2] => [Microsoft][SQL Server Native Client 10.0][SQL Server]Conversion failed when converting from a character string to uniqueidentifier. [message] => [Microsoft][SQL Server Native Client 10.0][SQL Server]Conversion failed when converting from a character string to uniqueidentifier. ) ) i've already converted and CAST the datatypes to uniqueidentifier this should only be a quick fix, but i'm too busy and have been looking at the monitor for too long! i will provide full access (usernames and passwords) to the MSSQL database and to the host control panel as well as the link to the screen that is causing the problem. This database is a prototype and we will be looking for a developer to create the full version of this in the near future, anyone who demonstrates their efficiency with this task will be highly considered for a long term contract.