Hello,
Many thanks for your suggestions, I believe it happens at all the workstations in their office, which is the only place in this site that this application is installed.
I will find out what specific areas they are in, this user does tend to leave everything open, but it is only our application that crashes.
I believe that we have already checked for rogue DLL's but will also double check this.
Will get back with some more info.
Nicole