I just recorded a new region on Logic Pro 8 and noticed the time bar turned extremely red as the playhead passed over it. Now on Playback the region turns violet behind the playhead and then eventually red if I play over the same area a few times. Scrolling the affected area out of the window and back fixes it but it just returns again after the playhead has passed over it a few times. Enought times and it glows red completely obliterating anw waveforms or text. Very strange.
I found an answer in an older post. It was a memory issue caused by running many apps at the same time. I think I had six going. Solved by restarting.