I found these Safari fixes at MacFixit. Unfortunately, none of them work for me. However, they may work for someone else. So FWIW:
Safari won't launch: Check for corrupt bookmarks
There are a variety of causes for an inability to launch Safari, including:
\t◦ \ta corrupt general .plist file (delete ~/Library/Preferences/com.apple.Safari.plist
\t◦ \tcorrupt caches (delete the contents of ~/Library/Caches/Safari
\t◦ \tproblematic plug-ins (look in /Library/Internet Plug-Ins and ~/Library/Internet Plug-Ins
Generally deleting (or temporarily removing from their current location) any of the aforementioned files will not result in the erasure of any important data. The launching problem will be solved and you'll only need to reconfigure a few settings.
One source of failed Safari launches, however, is more problematic. If the bookmarks.plist (~/Library/Safari/Bookmarks.plist) file becomes corrupt and prevents a Safari launch, the brute solution is to simply delete this file. This will, however, result in the deletion of all currently stored bookmarks.
There are two options if you don't want to lose your bookmarks:
\t◦ \tMove the file ~/Library/Safari/Bookmarks.plist to a different location then restart Safari, which will cause the creation of a new bookmarks.plist file. Then use a utility like PlistEditPro to extract your old bookmarks manually and re-enter them.
\t◦ \tAs discovered by MacFixIt reader Art Robertson, navigate to~/Library/Caches/Metadata/Safari/Bookmarks and find the file that is your default home page (you can do this by selecting "Get Info" in the Finder and looking under "More Info"). Sometimes launching this file will result in Safari being correctly able to access the page and properly launch.