MacOS – Applications frequently become permanently unresponsive

I frequently have applications become unresponsive while they're in the background. That is, I'm not able to switch back to them*, and the Force Quit Applications window shows them as "Not Responding". They never become responsive again no matter how long I wait.

Some features that make this problem unusual:

• It's not limited to one or two applications. It's happened with MS Office applications, Textedit, BBEdit, Evernote, OpenOffice, Preview, and others.
• It's not limited to times when the application is doing something intensive. In fact, it usually happens to apps that have been in the background and not doing anything in particular.
• I've never observed it to happen to web browsers or to music players that are playing music.
• It doesn't seem to be triggered by other applications doing things that are CPU or memory-intensive.
• Other applications are not slowing down or hanging when it happens.
• The non-responding application shows < 1% CPU usage in Activity Monitor.
• If I force quit the application and restart it, then the problem usually doesn't recur quickly.

Does this suggest any potential causes or troubleshooting steps? I know the usual advice is to either start with a new account or disable all of my other programs and customizations one by one, but I'm hoping that the specific features of this problem might help me proceed in a more targeted way.

System info:
Macbook Pro, 2012 model, OS 10.9.4, 8GB RAM, 500GB HDD with 160GB free

* Specifically, what I mean is that I can cmd-tab to the application's icon, but the program in the foreground doesn't change. If I expose one of its windows, I can move the window around, but clicking in it doesn't bring the application to the foreground or affect the contents of the window. Notably, I do not get the beachball / pinwheel pointer when hovering over it, as I do in other cases when an application is stuck.

update:

Here's the system log from an incident when OpenOffice became unresponsive. I discovered it at 8:17. I don't know exactly when it failed, but the last log message and the last revision time on my auto-saved files is 7:46, so I assume it was within 5 minutes of that. Note that the OpenOffice error in the log (appears as soffice) shows up twice, five minutes apart, meaning that the first one wasn't fatal and so I suspect the second wasn't the cause of the hang either.