I had installed rapport software on my mac today and Safari did not like the address bar that it automatically showed an icon.
I removed that in the preferences. Used the guide that someone else suggested from something similar.
Here is what helped:
dump your safari .plist file.
Quit Safari, open up a Finder window and go to your home folder, then the Library folder within that, open the Preferences folder and select the file called "com.apple.Safari.plist". Drag this to the desktop or other easily found location then restart Safari, the file will be automatically recreated with default settings. Try going to the sites you've had problems with, if this solves the problem, delete the old plist file, if not you can either put the old one back in place or keep using the new one. Hope this helps.
I restarted my mac, but it won't open.
Process: Safari 
Version: 5.0.3 (6533.19.4)
Build Info: WebBrowser-75331904~2
Code Type: X86-64 (Native)
Parent Process: launchd 
Date/Time: 2011-03-22 13:58:06.182 -0400
OS Version: Mac OS X 10.6.6 (10J567)
Report Version: 6
Interval Since Last Report: 447309 sec
Crashes Since Last Report: 23
Per-App Interval Since Last Report: 436318 sec
Per-App Crashes Since Last Report: 20
Anonymous UUID: DC83C206-E41E-4F97-A976-590C59F26787
Exception Type: EXC_BAD_ACCESS (SIGBUS)
Exception Codes: KERN_PROTECTION_FAILURE at 0x0000000100b1b0f0
Crashed Thread: 0 Dispatch queue: com.apple.main-thread