Keep your Apple Mac OS X up to date. Also here the Supplemental Update for Mac OS X 10.7.3

What's New:

The 10.7.4 update is recommended for all OS X Lion users and includes general operating system fixes that improve the stability, compatibility, and security of your Mac including fixes that:

• Resolve an issue where the “Reopen windows when logging back in” setting is always enabled
• Improve compatibility with certain British third-party USB keyboards
• Address an issue that may prevent files from being saved to a server
• Improve the reliability of copying files to an SMB server

For detailed information on this update, please visit this website: http://support.apple.com/kb/HT5167.

For information on the security content of this update, please visit: http://support.apple.com/kb/HT1222.