While there are many potential causes to this message, when printing from CU*BASE GOLD this error can occur when the print session for that specific printer has locked up.  The server still sees the session as being active, but the session itself has encountered errors.  To fix this, please close out of the print session then sign back in.  If problems persist, this could point to an issue with Windows itself.  It is recommended you contact your IT support provider to troubleshoot the issue.