If you return to ContentBarrier, are the changes you made to the settings not filtering still as you left them, or did they revert back to the default settings? If they did revert back, use the "Disk Utility" program in the "Utilities" folder inside the "Applications" folder to "Repair Permissions" on your hard drive. This will usually solve this problem.
Are you using any type of "web accelerator" software? These packages often act as proxy servers that run directly on your machine and use the address "localhost" to route your web request through. The address "localhost" is not filtered by ContentBarrier due to the problems that this may create for the Operating System. Some web accelerators can be reconfigured to use another address.
This might also be caused by your browser's cache settings. When you switched to filtered access, your browser still had these pages in its cache, and rather than reload the page from the internet, it reads the page from its cache files on the hard drive. The browser cache is separate for each user account on the Mac.
In Safari, there is an "Empty Cache" command under the Safari menu at the top of the screen. Use this to remove the cached pages.
In Internet Explorer's preferences there is a section for the cache settings. This is usually under Web Browser -> Advanced, but may vary depending on the version you are using. Here you will find a button to 'Empty the Cache', this will solve this problem this time. It will be better to also make the 'Update Pages:' setting either 'Once per session' or 'Always'. This way the cached page files will be updated at least when you relaunch IE if set to once per session, or IE will not rely on the cache at all for page files if set to Always.
The cache feature of browsers was developed as a way to speed Internet access at a time when most users were using slow dial-up access. If the browser could read the files from the hard drive rather wait for a download each time a page was asked for, it would appear much faster.