Firstly: Welcome to techspot!!! Hope you like it here and stick around for a while...
now, your problem...
I don't know. But if it turns into a brilliant white dot in the middle of the screen, and your screen disappears, start worrying. lol (unlikely though).
When you say three quarters of the way across the screen, do you mean not all the way across, a vertical line, ... ? Is it intensely light?.....