USB Ports

I was trying to record some more LPs tonight and when I turned on my computer the software didn't recognize the USB turntable.  So I thought that the USB ports were not working. I found the card with a different set of the USB ports and reseated it and the software was able to recognize the turntable.  The next day I was going to record some more LPs and the software didn't recognize the turntable again.  So I plugged the turntable into the old USB ports and the software recognized the turntable.  The next day the turntable wasn't recognized again and a screwed around with the USB ports again until it worked.  Then somehow I realized that I needed to turn on the turntable before I turned on the computer.  From then on the software always recognized the turntable.