At http://blog.roblox.com/?p=1788 it says
If you are still experiencing issues, here are two things to try:
Restart your computer and try again. Seriously, I’m not just telling you to do this. We think it should fix the problem.
If that doesn’t work, please post in the Technical Support Forum. ROBLOX engineers will be paying especially close attention to this forum for the remainder of the day.
but there might be another way
1. Start task manager(CTRL+SHIFT+ESC)
2.Goto processes tab
3.Search for stuff that have the word ROBLOX in it
4.End all processes that have the word ROBLOX in it
it worked for me once
Roblox engineers?
What Roblox engineers?
I've only seen 2-4 people that like me, actually know what to do to fix most of the problems posted here.
But other than that, nothing.