NT Print Server - Excel - and HP4

[richsabe]

I have a Dell 2400 running NT4 (SP6a) with 512 MB RAM that acts as print server with about 20 printers connected. Ten of these printers are old HP4 printers. The problem is that at random intervals these HP4 printers will stop working in Excel. It usually starts with one printer then throughout the day it spreads to the others. All other applications will continue printing fine, but Excel files won’t print till the server is restarted. When you “print” an Excel file you see the hourglass (as normal), you see the file get to the print queue (as normal) but nothing comes out of the printer. Looking at the server I see nothing unusual at these times compared to when things are working. The other thing is the randomness of the event (i.e. if it happened today and I restart the server it may happen again tomorrow, or it may be 6 weeks). One final note: while the HP4s stop working in Excel they print fine in everything else and the other printers never stop printing (even Excel files print to the other printers). Any ideas will be appreciated