Stop 10.7 Server running a screensaver on the LoginWindow

edit /Library/Preferences/com.apple.screensaver.plist to read

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
 <key>loginWindowIdleTime</key>
 <integer>0</integer>
 <key>loginWindowModulePath</key>
 <string>/System/Library/Screen Savers/Flurry.saver</string>
</dict>
</plist>

Or download the file here

com.apple.screensaver.plist

or run this