The first error is due to a problem with how that particular system is representing the computer to the domain. The prompt you get is from Windows. The COMException generated and not handled is a bug in the library which I have fixed and will be released in 2.3.2 shortly.
The second error is a permissions problem with the account used to initialize the TaskService. If no account was specified, it is the local account. That account does have permission to make changes to the task.
The second error is a permissions problem with the account used to initialize the TaskService. If no account was specified, it is the local account. That account does have permission to make changes to the task.