[xubuntu] Xfce4 Unstable

Getting confused here. I've written some simple scripts to transcode videos that work perfectly some times, and not so great at other times. For example, I just ran "2mkv" against a single file is a separate folder, and got an error message upon completion that it could not move the original file to the directory "old", no such folder and yet the script quite clearly says on line 3 mkdir -p new and on line 4 mkdir -p old. Nowhere in the script are any folders removed.

I have another script that employs ffmpeg's af volumedetect to find the volume level and apply the difference between that and the ideal level of "0" (89 db). As bash does not handle floating decimal points I've had to call up bc to handle the mathematics end of things and, again, sometimes it adjusts the volume level and sometime it does not.

It isn't just my scripts. In Gnome Sudoku you can right click a square to enter in possible values, again, sometimes yes, sometimes no.

Now, I'm the kind of person who leaves their computer ruing 24/7, and have noticed that things usually work perfectly just after a boot or login, but if its been ruing for some hours it is more likely to act up and the only cure is to logoff (which occasionally fails) or reboot. In the meantime this has caused me endless hours of frustration.

Just how stable is xfce4? Is there anything I can do to make it more stable? Please do not suggest moving to unity or kde - tried them, hate them. I like a simple interface - I usually don't even change from the stock settings. No themes, no bouncy icons, just my wallpaper selection changing every 10 minutes. How about Openbox for stability? It has the right-click menu I like, and I don't mind tinkering to get the settings right. Anyone have a opinion/suggestion/magic wand?

Amd 64 bit /w 8 cores, 16 Gb Ram, Watercooled (so it is not overheating)
Xubuntu 15.10 from clean install with all update.