It seems that when they are left on too long, one of two [if not both] of these things will happen:
1: The screen will get blank/lines. This means if the screen is displaying something and you try and scroll down, whatever is on the page will just wipe down... sort of like when windows freezes and you can move a window around and paint your desktop with it

2. This is the wierd one that makes me think 'rendering'. Occasionally, some other things happen, such as drop down menus being black and unreadable, and the arrows for the drop down menus and the back button changing and instead of displaying arrows they display the number 6.
I have attempted replacing one of the Profile 6 machines in hope that it was a hardware conflict. I used one of our old Dell Optiplex GX240s running Pentium 4s. We have had these machines running our catalogs for some time at the other library, but it seems that the new one now freezes, and once has had that arrow - 6 error.
I have also witnessed another GX240 at our library that has never had problems that displayed the drop down arrow as a number 6 about a week ago, but it hasn't happened since.
I didn't witness this but was told that other catalog machines running off of Dell Optiplex SX260s were doing the same thing.
Sorry this post is so long but I tried to separate relevant points with spaces for easy reading.
3---------------------(^o^)---------------------E [Don't make the E-Dude hug you!]
~Mike