Maybe someone won't make the same mistake that I did.
My Spaceball drivers would stop after a few seconds. I could start the driver, use the Spaceball, then it would quit.
I tried a different Spaceball, new drivers, old drivers, Serial to USB adapter (I use a serial 4000). Nothing kept it going.
Then it dawned on me - I ignored the 3Dconnexion webpage that popped up after installing the newest drivers last month. I had ignored it this time too. So I installed the newest drivers again, filled out that user page and everything is happy now.