Lotus 1-2-3 and Lotus Notes Incompatible

I cannot use the copy function on Lotus 1-2-3 spreadsheets if Lotus Notes is running simultaneously. The PC locks up every time. I then try to end the task and my machine crashes. If I shut down Lotus Notes then use 1-2-3, it works. I’m running Windows 95, 1-2-3 Millennium, and Notes R5. My computer is a Pentium III, 800 MHz, with 256MB RAM. This is also happening on a few other machines in the company.