SymptomsGuest operating systems and their applications work unstable on Mac OS X 10.6.5 and 10.6.6
CauseDue to the issues of memory management in Mac OS X 10.6.5 and 10.6.6, Parallels virtual machines may work unstable. This may happen with virtual machines working on Mac computers with more than 4CPUs and more than 4GB RAM, or with virtual machines running on external drives (USB or LAN storages). However, this problem doesn't affect virtual machines running on local hard drives of all MacMini, MacBook, MacBookPro and MacAir models.
ResolutionTo prevent your virtual machines from working unstable, do the following for each virtual machine:
1. Choose Configure from the Virtual Machine menu to open the virtual machine configuration.
2. Select Hardware > Boot Order.
3. Type the following flag into the Boot flags field:
4. Click OK to save the settings.
After that, you can continue working with your virtual machines. The problem will disappear.