We had another user report the same problem recently (although we have not been able to reproduce the problem ourselves). Could you try following the suggestions in that thread and if necessary follow the instructions in my last post to post screenshots of your Event Viewer here?
I just reread your post and realized I might have mis-read it the first time. If it is just a problem of finding the executable (and not related to the other thread I linked to) you should be able to find it by searching for “A89301” or “A89301 Configuration Utility”. If that does not work, the default location for the executable should be C:\Program Files (x86)\Pololu\A89301