"The underlying connection was closed" with SDL Tridion 2011 SP1 Template Builder - tridion

Question

When connecting to the CMS from Template Builder (TB) installed on a 64 bit Windows 7 laptop, we occasionally get the following error:
The underlying connection was closed: An unexpected error occurred on a receive.
at System.Web.Services.Protocols.WebClientProtocol.GetWebResponse(WebRequest request)
at System.Web.Services.Protocols.HttpWebClientProtocol.GetWebResponse(WebRequest request)
at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
at Tridion.ContentManager.Templating.CompoundTemplates.DomainModel.Model.Login(Uri contentManager, NetworkCredential credentials)
at Tridion.ContentManager.UI.CompoundTemplateDesigner.DesignerForm.LogonAs(Uri uri, Exception initialError)
This error only seems to occur when accessing from a client machine, and never seems occur when connecting from TB installed on the CMS server itself. This also does not seem to be CMS server specific, as the error also occurs intermittently when connecting to other environments and other client installs. I have tried re-installing TB, but the issue remains.
Has anyone else experienced similar issues, or have suggestions on what may be causing the error?

Answer 1

This can happen if there are too many connections open on the CM Server hosting the Templating Web Service.
Try restarting the server. If still continues add this following config in Templating web service:
<httpRuntime executionTimeout="3600" maxRequestLength="102375" ></httpRuntime>
This will leave the file in ../Tridion/Templating/web.config looking something like the following:
<configuration>
<tridionConfigSections>
<sections>
<clear />
<add filePath="..\config\Tridion.ContentManager.config" />
</sections>
</tridionConfigSections>
<system.web>
<httpRuntime executionTimeout="3600" maxRequestLength="1023750"/>
<authentication mode="Windows" />
<authorization>
<allow users="*" />
<deny users="*" />
</authorization>
<identity impersonate="false" />
</system.web>
<appSettings>
<add key="cmeWebRoot" value="WebUI" />
</appSettings>
</configuration>