Fix Version/s: None
This happens for me in VirtualBox. Not tested in other VMs or with real hardware by me.
Steps to reproduce:
1. Begin ReactOS installation and format partition in BTRFS;
2. Install ReactOS as usual, but wait around 15-20 seconds when setup asks to install a bootloader;
3. Continue a bootloader installation;
4. After reboot, VirtualBox VM fails with guru meditation.
It happens often for me.
See this YouTube video for details. The main action begins at 1:30.
UPD: Doesn't happen with FAT