id summary reporter owner description type status component version resolution keywords cc guest host 10966 Clicking Install Guest Additions has no effect jwdonze " Clicking ""Install Guest Additions..."" does nothing if a disk is already mounted in the CD/DVD virtual drive. Clicking ""Remove disk from virtual drive"" will allow Install Guest Additions to operate as expected. Version 4.18 automatically dismounted and disk and continued which worked nicely. There should at least be some type of dialog prompt for this situation. Thanks. Host: Windows 7 64 bit Client Windows 2008 R2 64 bit " defect closed guest additions VirtualBox 4.2.0 fixed Windows Windows