- do you have any overrides or haks?
- what's your OS?
- running as admin?
- If on Win 7 (seems to be most problems there), try typical troubleshooting like XP mode, disabling desktop and graphics enhancements, etc.
I wouldn't bother downloading more times. I'm sure you've got everything you need.
If you can get screenshots, that may help. And any more info can help.