Network Printers Offline (but not really)
If all else fails, you can disable SNMP monitoring in the printer's TCP port properties. You won't be notified when the printer becomes ACTUALLY offline, but you won't get false positives anymore.
We've seen somewhat similar issues here, but outside of a few high-end plotters that we print directly to IP for, we're hosting the rest of them off of a printserver, and your symptoms are not exactly the same as what we've seen, but close enough. I've got a few ideas for you, in the hopes that they'll help but nothing really conclusive :)
1.) Try restarting the local print spooler service on the workstation in question. (ex: net stop "Print Spooler" && net start "Print Spooler"). See if that has any effect.
2.) Navigate to the driver properties of the printer, on the workstation, select "Advanced", select "Print Processor", try setting "WinPrint" to RAW, or changing to MS_XPS and select RAW.
3.) Check the port on the local workstations that the printer is configured to use, is it valid or did it mysteriously dissapear? (We've seen THAT one before. Man, what a pain!)
4.) It's a long-shot, but see if a local firewall is blocking it. Disable any local firewall/ip filtering and test to see if it works. We've seen this before, but specifically in this situation: We're running Symantec EndPoint on all workstations and in some instances, the local Windows default firewall was showing as enabled and running and doing some funky, funky blocking. :)
Either way, good luck!
Restarting Print Spooler service on the client did the job. Restarting the service on the server didn't work.
Our network: Win7Ultimate 64bit + a bunch of Win7Pro 64bit without domain, only workgroup.
Did you change the default snmp community (public) ? Put it back online through the file menu once the printer is opened (or right click on it first.)