usually occurs with nvidia when alt+tabbing away from the screen when loading
See this guide
Go to C:\Program Files (x86)\Electronic Arts\BioWare\Star Wars-The Old Republic\swtor and delete just the file called discachearena then start the launcher and login.
I am currently having this issue. Only problem is when i go to that folder or do a search for that discachearena file i cant find it anywhere. I have tried reinstalling the game on both digital download and on steam (worked for 1 day using steam) even tried switching from my D drive install to my C drive install and still getting the pink box every time i load. Is there anything else i can do??
Unfortunately I don't have anything to help you. I too tried to find the aforementioned file and was unable to locate it. I have tried repeatedly talking to customer support and have yet to find an answer. I am at the point of stopping my subscription and stopping playing SWTOR! If you have anything else to try I'm game to try but I am out of options at this point. All other games I have work properly.
the diskcachearena file is in another folder called swtor once in the game folders , have you tried pressing alt + enter keys a few times ?
Play the game in fullscreen (window) mode the issue shouldnt occur
