Hi @sathya66 ,
a few questions, as it might be relevant information: what version of LSF/PM do you have? what Operating System? Is this LSF/PM on a single server, or on multiple Grid nodes? What is the underlying storage for this location? Local? Shared Storage?
To me it seems as if either the process or file are locked or not accessible, indeed. In any case, the real reason or problem, you will find it into the logs of the process manager and the disk journal, comparing timestamps and aligning historic events and log messages. have you got the chance to do this?