Nice. I agree with others, you should use "with recompile" statement . And more, if you are using MS SQL 2k5, you may use "with recompile" on a statement rather on the batch. 

And some comments about the network level in .NET.  If you would be having problem with that layer, I guess you would see a waiting status for your spid with something like 'NETWORKIO'.

Best Regards,

Igor.