I cannot pass an argument > 5KB to a CF web service

I cannot pass an argument to a ColdFusion 10 web service if it's greater than approximately 5 KB, regardless of the data type. If I do, the browser returns with a "This page cannot be displayed" message (in IE) or "Server not found" (in Firefox).  If I pass data to the same argument and it's < 5 KB, then it works perfectly fine.   Is there a setting somewhere in ColdFusion, IIS or elsewhere that's causing this that I can adjust?  I'm new to ColdFusion 10 and have never run into this with previous CF versions.  I'm running Windows Server 2008 R2 Standard - 64 bit- IIS 7.5.  Thanks.