Timeline Not Working Help!

I recently updated to 8.1 and as soon as I opened my project and played my progress I noticed that the timeline wouldnt move at all until I paused it I tried uninstalling it about 5 times and updated both adobe reader and quicktime and nothing worked its really stressing me out.

Does it happen with a new project also? If not, maybe your graphic card is reaching it’s memory limit on this project.