NT4 Server reports Printer Busy or Error

I have 5 print queues on an NT 4 server. Two queues frequently report a “Printer Busy or Error”. The print server appears fine and the printer reports ready. One is an HP 5si. The other is an older dot matrix generic. I’ve tried various drivers and used HP Jet Direct as well as Axis print servers. Recovery can be achieved sometimes by resetting the print server, printer or spooler service. I was origionally using SP 6a but backed down to 5 in an attempt to remedy this. I’ve seen this mentioned several times in various places but the only solution I’ve found is to remove SP 6a which didn’t help. Please help.