DB and mssql

I am using PEAR::DB on linux, php 4.3.2, with freetds to access a sql server database. I am trying to get more information on the problem, but everyonece in a while, it seems random, php will stop executing when I use the query method, php stops executing. I dont get an error, php just stops running. I can echo out things before the query call but not after. The query that is running can return large result sets,on the high end it will return 10000 - 15000 rows. I am am sql server novice so I am not sure where to start looking to see if the problem is db server side. I am just wondering if anyone has had this kind of problem before. I am not sure if it is something going on with PEAR::DB or if something is happening with the native php calls to sql server. I have not tried to do the query without using pear::db, but I am going to try that to see if I can get the script to error out that way. Thanks in advance.