If you change the option, then use File > Exit Directory Opus, then re-open Preferences, is the Opus also changed back then?
Can you think of anything the two machines have in common that isn't part of a standard Windows install? (e.g. other software, antivirus scanner, etc.)
If a crash dump is created matching the time of the crash, that may also help track down the cause. (Please link your account if you want us to look at a crash dump.)