Why am I getting an error from Web Services saying "User must be logged in to use order management!"?

You can use a command to stop and start the PowerPick Cross Enterprise Unit service.

Batch file to stop service (filename.bat):

net stop PowerPick.CrossEnterpriseUnit

If you're having issues with the service stopping, you can use CMD file to kill task (filename.cmd):

taskkill /IM "GP.CrossEnterpriseUnit.exe" /F

Batch file to start service (filename.bat):

net start PowerPick.CrossEnterpriseUnit