- This worm program behaves similarly to Happy99 Worm. It was originally spread by email. When the attached program file, PrettyPark.exe, is executed, it may display the 3D pipe screen saver. Once the worm program is executed, it tries to email itself automatically every 30 minutes (or 30 minutes ...www.symantec.com/avcenter/venc/data/prettypark.worm.html