Then you will have to go thru a systematic process-of-elimination of items in your user library folder.
From the Finder menu, choose Go->Go To Folder... and enter ~/Library. This will give you a finder window with a view into the Library folder for that account. The method you can use is: one by one, move (drag) items associated with Safari to the desktop (or another Finder window pointed at a folder that you've created for this process in Documents or some other convenient location). Then try to run Safari and see if there is a difference. If there IS a difference and it runs okay again, then the cause of the problem was something that you moved out of the Library. If it still doesn't work you can try the next item. Each time you move something from or to the Library, make sure you've quit Safari first. It will be a bit tedious but once you've found the culprit, you can move back much of what you pull out of Library, recovering things like your Safari bookmarks, etc.
Here is the order of items I would pull out in order to find the culprit:
~/Library/Preferences/com.apple.Safari.plist (file)
~/Library/Saved Application State (folder)
~/Library/Caches/*Safari* (any folder with safari in the name)
~/Library/Safari (folder)
~Library/WebKit (folder)
It's possible that with one of the folders of stuff removed, you will get a different failure indication from Safari. If so, you will have to return the whole folder and concentrate on individual items in that particular folder instead.
Good luck!!