upgrade from 5.2.20 to 6.0.4 hangs

[ThisEndUp]

I've tried to upgrade VirtualBox from version 5.2.20 to 6.0.4 on a Windows 7 Professional machine. If I'm very very patient, it gets almost to the end (progress bar gets all the way to the right) and then just hangs. Its delta read and delta write are zero, it uses < 0.01% CPU, but it does nothing...and we're talking at least an hour.

1) Was I supposed to remove version 5.2.20 before installing 6.0.4? If I do that, will I lose my virtual machines?
2) I can't be the only person to have this happen, can I? So what have others done that fixes this problem?

Thanks!

[BillG]

I would try removing the old version first. I usually do with major upgrades (version x to version x+1). You will not lose anything. Reinstalling a program does not affect its data files (and vms are just date files without the VirtualBox program).