I just experienced the exact same issue as the OP. Found a different solution :
I couldn't spot the variable in the Registry as suggested above, so tried a reboot into Windows10 safe mode , after which I was able to start Cakewalk fine and re-set the driver mode to ASIO. Once rebooted in normal mode, all was OK. Phew.
I believer this works becaase it disables the audio drivers which are hanging the normal Cakewalk restart, so probably a useful trick for many types of driver issue.
@Noel Borthwick - I also think that Cakewalk ought to figure out when it is caught in a driver issue loop, and offer the user some way to switch drivers (eg to ASIO) on a restart - this issue seems too easy to fall into, and then novice users are lost . Cheers !