There have been a few issues with the Acela including cracks in the undercarriages, plus electrical problems and mechanical issues (e.g. wind guards flying off and damaging the power lines) for a while, and some bad blood between Amtrak and Bombardier blaming each other for the problems. See for instance
http://www.washingtonletter.com/page...Aug19_2002.htm
http://archives.cnn.com/2002/TRAVEL/.../amtrak.acela/
http://www-tech.mit.edu/V122/N34/shorts_2_34.34w.html

When they canceled the Express trains in summer of 2002, partial service was restored inside of a week; there's though no predicting what will happen this time of course.