I noticed if you have photoshop open and visible at the same time as illustrator the text select tool starts acting irractically, flickering and making it hard to select text. Solution.... Hide photoshop... simple as that. It feels like if you have both windows open it doesnt know which program you're working on. Closing the other window solved the problem. I hope this helps as I spent a frustrating 1 hour trying to talk to Adobe Tech Help who were useless.