You've preempted my usual answer (install v1.7.2)
Does they both crash on startup before he/she has a chance to do anything?
I don't think there is much in common between the two versions.
One thing is the registration, maybe that has got corrupt somehow.
It might be worth explicity deauthorizing (ctrl-shift-D in library view) ~ but maybe you don't get far enough to be able to do that.
If you are comfortable using the registry editor, with no ADE running, try going in and removing
and everything underneath it.
Backup the registry first just in case; but I don't think it could do damage to anything apart from the already terminally ill ADE.
(Adobe's DRM system should be called inept, not adept)
From what I'm gathering, the customer sees the program crash as soon as it is launched so they don't have the option of de-authorizing it.
I'll offer this as an option to them but given it's editing the registry I cannot actually recommend it.
Thanks for the answer though.
Another thing possibly worth trying is IOBit uninstaller, http://www.iobit.com/advanceduninstaller.html
I don't know it will help, but it may well.
Uninstall with that may do a more complete job than normal uninstall and remove the offending registry entries, so that it works on reinstall.
(Still guessing it is the registry which is the problem anyway)
I can't vouch for it myself, but it appears to be reputable and well recommended.