Hello bbuxton,
We have not received any similar feeedback from other users (even if there were a few, which I might do not know about), which indicate that we do not have corrupted installer, otherwise there would be quite a lot of complains and reports from Windows users.
Anyway, can you locate the following address in the system registry (regedit.exe):
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-1-5-18\Components\620139E0B929C2837B208B4B3039995E\77451E1067830394886BEA87DEC0D340
Right-click on the key, select 'Permissions' from the context menu and grant full access to this folder. Then check the box to allow the same permission to be granted to this key's sub-folders (descendants). After that try to re-install PhotoScan or Metashape.
Some similar cases with other applications, according to my search for "could not open key unknown components", suggests to follow the instruction from Microsoft:
https://support.microsoft.com/en-us/help/313222/how-do-i-restore-security-settings-to-a-known-working-stateCan you please check, if any other these approaches help?
You can also try to remove the mentioned registry key (you can back-up it in advance), create a new one with the same name and try to run the installer again.
Also please check if Windows\system32\msvcr100.dll file exists, if not then you may need to install corresponding package of Microsoft Visual Studio Redistributable.