Windows XP/IE patch
If you want to stick to Internet Explorer the following appears to have solved the issue for me. (WARNING: This "patch" should remove all Google Adsense Ads from ALL sites you visit but I make no guarantees that it will work for you)
In My Computer open folder C: \WINDOWS\system32\drivers\etc (or wherever you have Windows installed) - look for file "hosts" Open this using Notepad (or other Text editor - DO NOT USE WORD/WORDPAD)
The hosts file may be empty, it may be not.
If there is an existing line which reads:
127.0.0.1 localhost
Then directly below this line(NO blank lines) type:
127.0.0.1 pagead2.googlesyndication.com
If the file is empty then type this as two lines with no space:
127.0.0.1 localhost
127.0.0.1 pagead2.googlesyndication.com
Then save the file and close Notepad. Shut down Internet explorer if running.
Open Internet Explorer again, come back to PPrune and fingers crossed problem solved. Basically what it does is to divert requests to go to the adsense pages directly back at your own computer so it never actually gets to the adsense page so the "page not found" errors do not occur and the back button works normally. (Fingers crossed! - it did the job for me)
DD