I replaced my despised ScanSnap S1300 with (sigh) another Fujitsu - the ScanSnap ix500. So far I like the ix500 almost as much as I disliked its predecessor. I bought it as a document scanner, but I'm using it to process several thousand prints currently stuck in a bin. The image quality is nowhere near as good as my Epson V700 , but it's a lot better than nothing. 
The next day though, my 2009 iMac (Mountain Lion)'s mouse pointer was frozen after screensaver clearance. The machine didn't respond to keyboard either; I hard to power cycle. This happened a few more times, though sometimes the keyboard worked. I found if I unplugged the peripherals, including my Mini DisplayPort external monitor, I could get things working.
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 do look for software issues though, and I realized I had two new apps running in my Menu Bar. One was called AOUMonitor and the other was Citrix Receiver.
Yikes! It's true that modern Mac issues are more often hardware than software, but those are two bad actors. AOUMonitor is Fujitsu's "ScanSnap Online Update" -- and Fujitsu is known for buggy Mac software. I only run ScanSnap Manager when I need it. Citrix is even worse -- my wife has to use it but it shouldn't be running in my account.
I needed both of them out.
AOUMonitor was easy. From my Admin account I found ScanSnap Online Update Settings.app and turned off auto-update. then I went to the Admin startup items and disabled AOUMonitor. I saw that ScanSnap Manager was also running for all users on startup, so I deleted that as well. I'll run it when I need it.
I figure AOUMonitor crept in when I uninstalled my old ScanSnap software and installed the new stuff, then updated it. I can't explain how Citrix Receiver showed up; until now I'd only seen it in my wife's account. Maybe some auto-update? Maybe I just never noticed it before. Disturbing!
Of course Citrix Receiver is an evil hack, so you don't find it Apple's User Startup Items list. I followed MacWorld's Take control of startup and login items (See also: Troubleshooting Startup and Login Items) and found several Citrix items in ~\Library\Library\LaunchAgents. I moved them to Emily's personal Library\LaunchAgents folder so they'd only run in her account.
Now we'll see if my mouse problems improve. Next thing is reducing the stress on the USB hub - and changing my screensaver away from Aperture slideshows.
- fn -
 Scanner tech isn't changing much -- just faster. So good photo scanners last a long time, but of course prints are going away -- so the useful lifetime of photo scanners is limited.
 Not the point of this post, but I just dump 30 or so photos in the feeder and scan to iPhoto at 300 dpi, color, minimal compression. The ix500 does a batch in about 15 seconds. Then I flip over to Aperture and organize 'em. The photos go into appropriate "Events" after I fix version names and set an approximate date, but I also create albums that match the photos to a code number (S1 ... Sn) on the photo envelopes. Then when I'm done it's easy to find prints or negatives that I want to scan property. I didn't return to high quality cameras until I went digital, so for most of these prints the quick scan is good enough.