Certain guides recommend deleting certain .dll files from your TA directory because they are not needed. (Such as this one http://switeck.tauniverse.com/tahelp.htm )
DO NOT DELETE online.dll! This file is required for hosting of IGW games to function correctly. If you delete it, you will need to reinstall TA and patch it back to 3.1c, or ask someone for the file from their TA installation.