SAP spool print error on prodution server

Hi Experts,

We have production live system ECC 6.6 where print goes from sap continuously day night.

There are 12 users which printer attached to there system individually (no network printer)

Printer setting as below

Output device : LP01

Device type : SAPWIN Rel.4.X

Access Method: F: Printing on Front End Computer

Printer : _Default

There is issue while printing...some print going smoothly without error and some in error.

Users are facing following errors (sp01 status)

1. Fatal error during processing

2. (SAP)LPD was started, but connection not possible

3. Consistency error: Invalid program status

There are 4 spool work process set in Profile parameter

Please advice the solution

regards,

Devendra