Quicken Classic for Windows Data Entry Problem

Since the most recent update, I've been unable to enter transactions or any other entry after 1st starting the program. I was thinking that some process was running in the background that was controlling the cursor such that I'm unable to click on a field and enter data. The spinning wheel displays every 1 or 2 seconds which stops me from using the keyboard. I tried several actions to stop the spinning wheel, and finally found that opening Norton 360 stopped it, allowing me to cursor to a field and enter data. Happened again this AM, so I opened Norton and entered transactions. I finished, closed Quicken and shut down the computer.

I turned the computer back on about 1/2 hour later and opened Quicken because I missed entering a few transactions. Lo and behold, the problem had stopped. I was immediately able to enter data in fields again, just like before the last update.

Now, I don't know whether there is a conflict between Quicken and some other program or if Quicken had been updated with a fix. I thought it might be a system issue so I checked CPU usage which was fine (21%) and read/write access to hard drive and lack of hard drive capacity which were also fine.

Anyone else experiencing this issue since the most recent update? Alternatively, anyone know what might be causing the problem? I can't seem to find the cause. Thanks!