Pixma MX720 Scan buttons grayed out

[bookmanjb]

After years of problem-free scanning, I'm having a problem that I can find no solution for after searching the web.

I'm using a Pixma MX 720 with an iMac, running 10.13.6. 

What's happening is that after I press the Open Scanner button in the Printer Sys. Pref, I get a gray window with the 3 buttons along the bottom grayed out. I downloaded the latest scanner driver for my model but it made no difference. 

Any hints as to how to fix this will be much appreciated. Thanks.

[bookmanjb · Accepted solution]

Never mind. I restarted and all is now well. Can't believe I didn't try that before posting.