Hit an unusual one when creating Web Applications on a Farm. Despite having gone through the process without any problems on two other farms, one particular (existing) setup fell over on every single Web Application I tried to create. It manifested itself in an IE unable to connect to server error, but when you go into General Settings the following error is shown.
Not entirely sure what the cause is, but the fix is quite simple.
Log onto the Central Admin machine using Remote Desktop Connection, open a SharePoint 2010 Management Shell and run the following script:
$w=GetSPWebApplication <%WEBAPPURL%> $w.HttpThrottleSettings $w.Update()
You can now go into General Settings and carry on as normal.