We have switched to transparent proxy but the internet browser is picking up a proxy settings from a old proxy servers

Hi

I am having issue with users. We have switched to transparent proxy but the internet browser is picking up a proxy settings from a old proxy servers that is not being used any more.
.

There are three group policies that are applied:

First one was the default domain policy- applied at the domain level
Second was the student policy applied to the - where the users are located
Thirdly was the workstation policies- Where the workstations are located.

I removed all the policies from the Group policy management console and still the internet explorer is picking  proxy settings of a old proxy servers.

Not sure how the proxy settings of a old server is being picked from.

Is it possible to run a report and find from where these proxy settings is being picked from.


Any help would be great.
Thanks