Ouch, that's not good. There is no way you should attempt to alter the stack settings manually. Perhaps try updating your virus scanner and running it again. Your config.sys file is probably corrupted.
For your knowledge the "stack" does pretty much what it sounds like. A program has the ability to "push" and "pop" data onto and off of the stack. You can think of it kind of like a pez candy dispenser. You can put a candy into it and get it out later, but the only catch is that if you put another candy in after the first one, you have to remove the second one before you get to the first.
In electronics terms this would be called a "shift register" or a FILO buffer.
Normally the operation of the stack is controlled totally by windows itself and if you are getting this error you have a potentially serious problem that may likely require a clean install of windows to fix.
