If you have received any errors in result of an custom GUI then please download the attached file (17.8 clean GUI) then extract the contents of the zip file into your Anarchy Online installation folder (typically C:\Program Files\Funcom\Anarchy Online\cd_image\) it will ask if you would like to overwrite these files and you would want to click yes. This clean GUI should allow you to access the windows normally.
If you have any issues in relation to the 17.8 clean GUI then please let us know by posting in detail here.