GMAT Strategy

I took the GMAT test yesterday, and was shocked. Yes, I didn't do much prep as I didn't need that much of a high score. I finished about a half of OG, and was confident enough to do as good as others do in their first attempt - low 600s. Yes, english is my second language, but i've been in the US for about 8 years, and thanks to my "excessive" and "uncontrollerble" desire in learning english, I am more comfortable in this language than my first. I wasn't over confident, but the fact that I spent so much time learning english and that I have bachelor's and master's degree in the US gave me comfort to certain extent as the score I need isn't too high. So I took the test, and the number said 490. How can this possibly happen? especially the verbal section was unacceptable, 20 out of 60. I felt pretty good during the verbal section, and was almost certain that I was answering correctly at least two thirds of them. i also was able to finish the section with 5 minutes of luxury.

I'm trying to think that it's ok and give myself a second chance, but the real problem is, I don't know what I don't know. I am solving problems here and there including those questions people put up on this forum, but scarily, I can tell what the correct answer is and why the rest of the choices aren't!!!

I need your help big time. I don't wanna be an a-hole, not admitting my loss, but the only explanation that makes sense is the computer generated a wrong score. I am very scared to retake the exam. I need an old priest and a youn priest.