Not all the errors you get with the infamous blue screen of death are short and easily comprehensible. If you get a "Driver unloaded without cancelling pending operations" you may not know what to do. Fortunately, we do and in a few moments will show you how to deal with it.
Sometimes when you get the Blue Scren you know what happened. An application crashed, you removed a file you shouldn't have, or you tried to do accomplish too many tasks at the same time. But when you get an error DRIVER_UNLOADED_WITHOUT_CANCELLING_PENDING_OPERATIONS you may certainly feel lost. To put it in human language: your driver stopped working, but since you had some operations going on your computer the system defended itself by projecting the BS.
Interestingly, this error (with the stop code 0x000000CE) appears way more often when you emulate a system using a virtual machine in VirtualBox or OracleVM, as well as non-standard environments, for example BIOS-emulating Bootcamp. Furthermore, this particular BS materializes usually on Intel-based comptuers (including Macs) but rarely shows up on AMDs.
So, how to deal with it?
1. Update your drivers. Make sure you have the newest stable release of your drivers installed. It is especially important with system drivers and video drivers. If you are not sure how to check your drivers' state, use a program, such as Device Doctor.
2. Remove or disable the driver that causes problems. This works for emulated systems: after booting into Safe Mode with Networking (F8 at the start) go to the console and remove all the drivers that cause problems, these are usually intelppm.sys that can be found in C:/windows and C:/windows/system32. Remove all temporary files associated by typing CD%SystemRoot/Inf/ and DEL OEM*.inf, or disable the driver in command prompt by typing sc config intelppm start=disabled. Finally, provided that you use VirtualBox, reinstall Guest Additions. Reboot the system.
3. Update your emulating program. If your VirtualBox or Bootcamp are not up-to-date, they may cause problems by themselves.