I have customized my KDE environment (just simple stuff, like background, clock, etc) and ran Linux-Live-6.1.5 to create an new build. The build boots fine and everything seems to be in its proper place. When I enter the KDE environment, I can open a terminal and enter a command, such as aircrack-ng (no arguments, it just prints out a help screen). As the session progresses, I slowly lose the ability to run commands.

For instance, entering the command aircrack-ng once more results in this error:
bt ~ # /usr/local/bin/aircrack-ng  Cannot execute binary file.
The command is still there and is still marked as executable. If I am quick enough once this starts to happen, I will usually have enough time to logout of the KDE environment. However, this behavior follows me back to the main terminal environment. Almost any command entered now results in this error. The only commands that will execute seem to be internal bash commands.

It's like I have been slowly bled of any and all privileges. The only way out of this is a reboot.

Entering whoami reveals that I am still "root".

Now, on the otherhand, the flux environment operates correctly for as long as needed (but a working KDE environment is much nicer).

I was hoping that there were linux experts around that had some idea why this was happening.