Slickbear - 8:05 pm on Jul 27, 2011 (gmt 0)
I just joined the forum so that I could throw some light onto the problem. I too have been running in circles with a similar issue and found a fix and is working for me.
The problem is the .htaccess file applies to everything within its directory including all other directories/folders within, so the problem is you are identifying the user agent and telling it to redirect to another directory within , but as soon as the request reaches the destination folder it executes the original rule again resulting in the constant loop.
With that explanation aside the solution is as follows:
Create a second .htaccess file with the following:
#Begin user agent loop fix
#End user agent loop fix
Now place this .htaccess file in your destination directory / folder where you want the user to actually be.
Now when the original request is executed and reaches the destination it tells it not to execute any more rules.
Simple as that!
Hope this helps everyone out there that has been pulling their hair out :)