Had this problem all the time, Ad-aware does not update. It was suggested on the ad-aware forum that my ISP is at fault so I contacted NTL. Here is the reply:-
Thank you for your recent contact.
The caching of web pages on the ntl system is done automatically and is unavoidable from a customer point of view. This is a feature of our service and is designed both to improve browsing speeds for the customer, and to reduce network traffic across external networks. A refresh of any cached web page can be forced by using the key combination ctrl/f5 from within internet explorer. Please note pages written containing dynamic or frequently updated content, should be written by the coders to include cache control, click here is a good example of a correctly written page.
Caching will only affect http traffic on port 80 and will have no affect on downloads or automatic updates.
For more information on NTL proxy servers please see click here
I hope the above answers your query, however, should you need further assistance, please don't hesitate to contact us again.
So reading into the reply seems that the code for the update is at fault. I will try the Ctrl/f5 combination see if that helps. Next I will try the information on "chetnet".