I ran into what seems to be a very serious bug with the symbolic engine. A rather basic Integral is evaluated wrong. See the picture what it look like. The MC version is MC14-M030. The bug does not show up with version 11. From collabs I heard that the bug does not show up with Mathcad14-version 220.127.116.11 (is this M011??). This would be rather curious. Anyway - anybody figure out whats going on her or has a workaround? Feel a little bit concered not knowing what other results will be as wrong in oter calculations. W. Exinger 15.3.2010: According to PTC-Support the bug is known and already fixed in M040. He couldn't tell me when M040 is scheduled. Personally I thought the next release would be MC15 in June or July.