IIS+PHP+MSSQL strange issue

[levitymn]

We are running into this issue with PHP running in iis 6.0 and connecting to a MSSQL database located on another server.  It works fine for about a week of heavy use and then suddenly the server will not be able to connect to the mssql database until IIS is restarted.  I cannot find any reference to an issue like this anywhere.  I have reviewed all the code to make sure that all connections are being explicitly closed even though we are not using pconnect.  Has any one run into an issue like this?  I should also mention that this server has cold fusion running, has for years and CF has had no problem until we started making lots of connections with php.