I'd love to look at logs.
Also, try clearing logs folder - /Users/<username>/Documents/My Tableau Repository/Logs.
Downloaded. Please delete them now.
Do you have a Preferences.tps file in your repository folder? If yes - what's in it? (Open with Notepad)
Also, if it's there - can you rename it to something else and try launching Tableau?
If it's not - can you create a new file with that name, paste this inside and save?
<?xml version='1.0'?> <workbook> </workbook>