First time after starting windows, I can simulate without any issue some projects. However, after a while, windows as "RPC not available", "ORPSRVR-2004 File does not exist" - from AMS Simulation Manager, and" Orcad contains an invalid path" start appearing and the only solution is to restar windows again, or close completely all Orcad and Pspice tasks before reopen the programs again.
This error can come in case pspice is not able to find a required simulation file.Check if you have moved or deleted any file from project location.Also open on a sample design accessible from \tools\pspice\capture_samples and check if the problem is reproducible.