I had this problem for a short while, then it suddenly went away. I don't know exactly what fixed it, here are all the steps I took in my attempt to fix it

1. Clear your browser's cache and cookies
2. Try resetting your internet connection (turn off the power and turn it back on)
3. Reinstall Adobe Flash Player
4. Refresh your page every time the problem occors, it should eventualy work
5. Leave the page open for 10 minuites (look at the clock)
6. Restart your computer
If it still doesn't work let me know.