SOLVED!!!   I had the same problem and read through this thread finding nothing to help at all.  We had over 800 in print queue and couldn't get them to print and or go away.  We had the first invoice in there that was an inactive customer and had no invoice number.   Maybe that was the hold up originally so I just opened that invoice and unflagged to be printed.   The other invoices in there will print and clear out now but I can't do all 800 at once or it crashes.  Now it seems the problem is that there are too many in there.   Maybe this can help Quickbooks at least solve the problem?