The following is a collection of rules which any person, who works with computers, needs to know. Most of these have been around awhile, and I do not necessarily take credit for their invention. Never assume anything.
All software has bugs, even the stuff thats been around forever.
Just ask Intel about pentium floating point calculations, or Microsoft about the Windows calculator. If something stops working, then something has changed. Figure out what changed, and you might figure out how to fix it. This applys to more than just computers. Never assume you're right.