Kev,
PUBLIC variables are the bane of existance. These little beasts will crash your code in ways that make it virtually impossible to debug. They are like an infection that spreads throughout everything that runs, sometimes harmless and sometimes disasterous. These viruses should be erradicated at all cost. Treat them like HIV and kill every one you see. Find some other way to do what you need to do and NEVER use a PUBLIC variable. Be asure to always declare your variables as private or local so that anyone else's publics can't creep into your running code and hurt you (software condoms).