I reported a problem with TCSH: But if I issue "d:/tcmd9/tcc.exe" (TCC starts in the console), when I exit TCC, TCSH "encounters a problem" (message box appears) and TCMD gives the message free(0x7fbdad88) bad block. (memtop = 0x7fc10800 membot = 0x7fbb0000) This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. I have tracked this down to the "UpdateTitle" directive. The problem occurs with "UpdateTitle = No" and does not occur with "UpdateTitle = Yes". Recall that the problem occurs when TCSH executes its precmd alias (title "$cwd") after the started 4NT process exits. A wild guess is that something happens to the state of kernel32.dll (closing a handle that shouldn't be closed?). I appreciate your point, Rex, that 4NT shouldn't even be able to influence what happens after it exits. I suppose TCSH's author might say something similar. Nevertheless there's a rather peculiar dependency on 4NT and the UpdateTitle directive in particular at play here.