I only run ScanSnap Manager when I need it. AOUMonitor is Fujitsu's ' ScanSnap Online Update' - and Fujitsu is known for buggy Mac software. Yikes! It's true that modern Mac issues are more often hardware than software, but those are two bad actors.
One was called AOUMonitor and the other was Citrix Receiver. I do look for software issues though, and I realized I had two new apps running in my Menu Bar. In my recent experience this kind of problem is most often hardware related - perhaps a problem with my USB bus (7-8 devices on one old hub!) or Firewire bus. I found if I unplugged the peripherals, including my Mini DisplayPort external monitor, I could get things working. This happened a few more times, though sometimes the keyboard worked. The machine didn't respond to keyboard either I hard to power cycle. The next day though, my 2009 iMac (Mountain Lion)'s mouse pointer was frozen after screensaver clearance. The image quality is nowhere near as good as my Epson V700, but it's a lot better than nothing.
I bought it as a document scanner, but I'm using it to process several thousand prints currently stuck in a bin. So far I like the ix500 almost as much as I disliked its predecessor. I replaced my despised ScanSnap S1300 with (sigh) another Fujitsu - the ScanSnap ix500.