Apple has released a new update for Mavericks, 10.9.4 available via Software Update or via download from the Apple website
The OS X Mavericks 10.9.4 Update is recommended for all Mavericks users. It improves the stability, compatibility, and security of your Mac.
Fixes an issue that prevented some Macs from automatically connecting to known Wi-Fi networks
Improves the reliability of wake from sleep
Includes Safari 7.0.5
For detailed information about this update, please visit: http://support.apple.com/kb/HT6281
For detailed information about the security content of this update, please visit:http://support.apple.com/kb/HT1222