StuffItCM.plugin (in /Library/Contextual Menu Items) is probably causing the crash.
Patch available here;
ftp://ftp.smithmicro.com/stuffit/stuffitcm.plugin.zip
To apply the patch, do the following:
Download the patch.
Unzip the StuffitCM.plugin.zip file.
Go to your Mac's /Library/Contextual Menu Items folder.
Delete the existing StuffitCM.plugin file.
Insert the new StuffitCM.plugin file.
Log out then back in.