Wake up unresponsive DVD drives, restore transparency effects and keep clocks in sync
Guest OS doesn’t respond to new CDs/DVDs
If you’re using VirtualBox to run a guest operating system (OS), such as an older version of Windows, you may find it fails to recognise your optical (CD/DVD) drive. A quick Registry tweak should fix the problem. Back up the Registry first, by creating a system restore point. Then, in your guest OS, type regedit into Start and press Enter to open Registry Editor. Navigate to HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\cdrom. Right-click AutoRun in the right-hand pane and choose Modify. Change the ‘Value data’ field to ‘1’ and then restart the guest OS.
Unable to access BIOS settings
VirtualBox doesn’t allow user access to the BIOS in the same way as a real PC, so tapping Delete or F2 when starting a virtual machine won’t work. To access settings that you’d normally find in the BIOS, such as the drive boot order, right-click the virtual machine’s name then choose Settings. Next, click System on the left-hand side, then select the Motherboard tab.
Can’t install Linux in virtual machine
If all your attempts to set up a Linux guest OS using VirtualBox fail, first check the specifications of your host PC’s processor by pressing Win+Pause/Break (the Pause/Break key is normally at the top-right of your keyboard). Linux can encounter problems on some older CPUs, including AMD’s Phenom or Opteron processors, so if you’ve got one of these it could be thwarting your attempts to install the OS.
The solution is to enable a hardwareemulation feature called Advanced Programmable Interrupt Controllers (APIC). Before installing Linux, rightclick the blank guest OS in VirtualBox and choose Settings. Now click System, select the Motherboard tab and tick ‘Enable I/O APIC’. Click OK, and then install your Linux distribution.
No bootable medium found
A virtual machine displaying a ‘FATAL. No bootable medium found. System halted’ error message means it’s unable to find a boot disc, such as a Windows installation CD/DVD. This typically means that an ISO file hasn’t been attached to VirtualBox as a virtual drive. To do this, click Devices, followed by CD/DVD Devices, then click ‘Choose a virtual CD/DVD disk file’ and navigate to the ISO file.
If there’s already a guest OS installed, then it could be an incorrect boot order (see ‘Unable to access BIOS settings’ tip). If this doesn’t help, then the virtual drive may have become corrupt. Restore from a backup or delete the guest OS and start over.
Guest OS’s time drifts out of sync
If a guest OS’s clock loses time (running slow before suddenly catching up), a probable cause is a power-saving feature of modern processors known as C1E or Enhanced Halt. This lets the processor save energy by taking breathers when little is happening – but it can play havoc with timekeeping. It’s safe to disable and the additional energy costs are negligible.
So, access your host PC’s BIOS then look for this option. With an older PC, access the BIOS (usually by tapping Delete or F2 after switching on). For newer Windows 8/8.1 PCs, press Win+C to open the Charms bar then click Settings followed by ‘Change PC settings’. Next, click ‘Update and recovery’ followed by Recovery, then ‘Restart now’ under the ‘Advanced startup’ heading. Click Troubleshoot followed by ‘Advanced options’ and then UEFI Firmware Settings. Finally, click Restart to launch into the UEFI BIOS.
Transparency effects not working
A bug in some versions of VirtualBox’s Guest Additions toolkit shuts off transparency effects in some editions of Windows. VirtualBox developer Oracle should eventually fix this, but meanwhile you can get around it by installing an older version of Guest Additions. Download ‘VBoxGuestAdditions_4.3.12.iso’ (www.snipca.com/16431), then start up the affected virtual PC and point to Devices, followed by CD/DVD Devices and then click ‘Choose a virtual CD/DVD disk file’. Now navigate to the ISO file you just downloaded, click to select it and then follow the prompts to complete installation. When you’ve finished, reboot the virtual OS.