Andy Nifong addresses the error You cannot open Microsoft Dynamics GP now because another user is entering Multicurrency access information in Dynamics GP.
You cannot open Microsoft Dynamics GP now because another user is entering Multicurrency access information. – Blog – andy.nifong
Install, Upgrade & AdminGeneral Ledger & FinancialsMicrosoft & the GP Ecosystem
Archived post from 2011. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.