Canon DR-1210C Scanner Problem

I have a Canon dr-1210c document scanner and am having what I think is
a driver/software issue. Through the custom buttons on the front and
Job Registration software I had programed in several scan types I use
frequently. Once I a single scanning job and try to press a custom
button for the next scan job, the scanner (or software) will not allow
me to start the next job unless I restart my computer. (This is a new
development. I'm not sure what started it, but up until last week I
could always scan multiple jobs without an issue.)

I went to the Canon site and downloaded/installed all the latest
drivers and software versions available. This actually made the
problem worse as none of the custom buttons would work. I uninstalled
everything and re-installed only the software that came with the unit.
Now I am back to being able to scan one job at a time, then having to
reboot my computer.

Any ideas?

Thank you,
YYY