Disclaimer: I have no real reason to share this batch of GMAT horror stories, other than to scare you just a little bit for no good reason. Pretty much everybody faces some serious time pressure on the GMAT quant section, and many people are forced to scramble on the verbal and AWA as well. So if you lose two minutes due to a computer glitch, it's pretty maddening. Two minutes won't destroy your GMAT score, but it might make you flustered and cause a cascade of errors.
In the past 12 months, at least five of my private tutoring clients have been affected by GMAT test-center glitches. This past weekend, two of them--one in NYC, one in DC--had issues. In both cases, the dudes working for Pearson VUE (the company that runs the testing centers) had a hard time logging the test-taker back into the system after a break. In both cases, the students lost a couple of minutes for the quant section. Pretty crappy.
In another couple of cases, the GMAT testing center dudes accidentally shortened the test-takers' breaks by failing to notice when the test-taker was finished with a section. When you're ready for a break after a section, you're supposed to tell the computer that you're ready for a break, and then raise your hand so that you can be escorted out of the testing room. Supposedly, the "escort" didn't notice when a couple of my GMAT students were ready, and a few minutes passed before the proctor noticed the test-takers' flailing hands. It isn't a big deal to have eight minutes instead of ten for your break, but it's still annoying.
And then there are the computer glitches. In one case, the system crashed during a break, and somehow restarted with several minutes already elapsed in the quant section. (I can't explain why these problems seem to occur between AWA and quant. GMAT hates you?) Another student faced a really bizarre glitch which prevented him from clicking on certain radio buttons--if I remember correctly, he was literally unable to select most of the answer choices, and had to click "next" with some questions unanswered. He complained at the testing center, but they couldn't really do anything about it. I don't think that he even finished the test. In both of these cases, the test-takers called GMAC every single day until they were allowed to re-take the GMAT for free.
Again, I have no real point here. I'm not trying to criticize Pearson VUE; generally, I think that the company does a solid job administering the GMAT, and I've had good experiences in their test centers. (The GRE is another matter--last time I took the GRE at a Prometrics test center, I was forced to an old, flickering monitor which made my eyes hurt. By the time I left, I felt like I'd been staring at a strobe light for four hours, which made me a little bit crazy.) As a full-time GMAT tutor who watches students spend craploads of time and money on the MBA admissions process, it's painful to see people get thrown off by these stupid glitches. But human and computer errors happen, and all you can do is roll with the punches. And if the glitches really affect your score, you can always bitch and moan until GMAC compensates you for the errors.