Officials of the College Board are still not sure what caused the error in the scores of 4,000 students who took the test in October 2005. Most of the affected students received a lower score than they actually earned, with some scores off by as much as 200 points. Many college admissions officers are now having to reconsider decisions that were based on faulty scores. Student complaints about the inaccurate scores prompted the College Board to investigate the problem in late December, but admissions officials were just notified about the errors this week via a mailed letter.