In the computer world, where the changes the user makes are often instantaneous, there is no room for ambiguous wording in commands and documentation.
See the above image of a menu item titled "Use Logging". Selecting the menu item might cause the item to be marked with a checkmark or negated, depending on what the programmer or the program's (incompetent) UI designer had in mind.
The problem here is that, taken out of context, the command "Don't Use Logging" could be displaying the current status, or it might be describing what will happen when the item is selected. Thus the item title does not make it clear if logging is currently on or off. You can find out what it means only by selecting the item. Of course, this might either lead to the desired result or it might have disruptive – or worse, destructive – consequences.
Negated item titles cause ambiguity. They make the user lose trust in you and your program. Therefore stick to positive forms of commands and status items. Don't say "Don't Use Logging" but instead use "Turn Logging Off". Instead of "Don't Use Lowercase" say "Use Uppercase". Train your user to look for checkmarks in menuitems. Use checkboxes to alter status instead of making pushbuttons negate their labels.
In the end, it all boils down to the fact that a piece of text may be read in a way you don't necessarily expect.