Safari Quitting Regularly While Using SafariSniffer... HELP???

Hi again guys!

I'm hoping that some of you may be able to help here. I'm running a late-2010 13" MBP so am still relatively new to the Mac world, and while the love is still strong, some little issues are starting to weaken the love just a little! I have had trouble with Safari lately, getting the message "Safari quit unexpectedly while using the SafariSniffer plugin..." on three occasions, along with the details below (not inclusive). Any ideas?

I'm not sure if it is relevant, but the issues seem to start around the time that I noticed the external display (Acer monitor) didn't go to sleep when I closed the lid on the MBP to put it to sleep (the display stays on regardless!

I've also got issues with iMovie '11, but that;s for another forum!

Looking forward to you good people helping out a little...

+Process: Safari [2073]+
+Path: /Applications/Safari.app/Contents/MacOS/Safari+
+Identifier: com.apple.Safari+
+Version: 5.0.3 (6533.19.4)+
+Build Info: WebBrowser-75331904~2+
+Code Type: X86-64 (Native)+
+Parent Process: launchd [163]+

+PlugIn Path: /Library/Application Support/SIMBL/Plugins/SafariSniffer.bundle/Contents/MacOS/SafariSniffer+
+PlugIn Identifier: com.yourcompany.SafariSniffer+
+PlugIn Version: ??? (1.0)+

+Date/Time: 2011-01-18 09:45:51.104 0800
+OS Version: Mac OS X 10.6.6 (10J567)+
+Report Version: 6+

+Interval Since Last Report: 352791 sec+
+Crashes Since Last Report: 2+
+Per-App Interval Since Last Report: 62061 sec+
+Per-App Crashes Since Last Report: 3+