I was recently in a tour of a professional games company and asked the question 'what was your most irritating beta bug?', he mis-interprated the question and answered 'any that gets released into the final version'.
My most irritating bug was having a loop->
for(i=0; i<10; i++)
{
//do what I had to do
if (this happens) {i=0;} //reset 'i' in order to start the loop again
}
What I didn't realise was that when I reset 'i' to 0 the loop was incremented after that statement and actually started on 1