Just because your error message also starts with the words 'Critical error. I have deleted your other post in what was an unrelated topic. To avoid duplication please ask your question once.
1: Download Microsoft File and Folder Troubleshooter Microsoft File and Folder Troubleshooter can find and fix common problems with file and folder operations, including Windows Explorer and File Explorer in Windows 7, 8, and 10. Cross posting is against the rules of these forums. If you are trying to create a new folder in Windows and can't, here are some possible solutions. Don't do anything not mentioned in the tutorial. Reinstall, and then follow the instructions in User Manual section 1.7: Creating your first virtual machine. So, I would start again: uninstall VirtualBox, delete the \.VirtualBox folder. You could undo this damage, but I don't know what else you've done. 3 Type a name you want for the 'New Folder', and press Enter or click/tap somewhere else to apply. (see screenshot below) 2 Press the Ctrl + Shift + N keys. 1 Navigate to where you want to create a new folder on your Desktop or in File Explorer (Win+E). This error is terminal, hence 'Critical error'. Create New Folder using Keyboard Shortcut. The error occurs when VirtualBox tries to create a VM folder in your Downloads folder, since of course an ISO file and a VM folder can't both use the same name. It also sounds like you changed your default machine folder to that of your Downloads folder. It sounds like you are trying to give the VM the name of your boot ISO file, which isn't a good start.
