In multi-user mode, QuickBooks Errors 6073 and 99001 appear when attempting to access a corporate file. The file is open on another machine, preventing access, according to error 6073. The error 99001 indicates a problem with network connectivity. Assuring appropriate file access permissions and confirming network setups and connectivity are necessary steps in resolving problems. Call 1.855.856.0042 to reach QuickBooks help for a successful resolution.