Prior to version 1.1.7 there was a bug in the WebDirect evaluation code that caused it to reply to all web requests through ISA server with the "WebDirect has expired" message. This defect has been fixed with version 1.1.7.
To fix this problem you can download the new evaluation version and install it over the old 1.1.6 version. This will not extend your evaluation period, but it will stop the expiration message from denying your normal web traffic.
If you know that you want to purchase the software anyway, then you can simply proceed to install the licensed version instead and that will also eliminate the problem (this approach has the benefit of course that WebDirect rules will start to work again!)
We apologize for any inconvenience this has caused to our customers!