This is really weird.. I added some printf's (see patch at end of message) to see what interval_id's XEmacs sees, here is the output just before the crash Completed: 131 Looking up: 131 (0) Removed: 7080192 Removed: 4377440 Allocated: 133 InList 133 Removed: 4377440 Allocated: 134 InList 134 Allocated: 135 InList 135 Removed: 4377440 Allocated: 136 InList 136 Completed: 134 Looking up: 134 (0) Fatal error: assertion failed, file event-stream.c, line 1214, !NILP (rest) XEmacs gets interval number 134 which it did allocate and put in the list just before. So it SHOULD be ok.... Perhaps somehow pending_timeout_list gets corrupted? Index: event-stream.c =================================================================== RCS file: /usr/CVSroot/XEmacs/xemacs-20/src/event-stream.c,v retrieving revision 1.45 diff -u -u -r1.45 event-stream.c --- event-stream.c 1998/06/13 04:28:43 1.45 +++ event-stream.c 1998/06/18 17:14:02 ＠＠ -1168,6 +1168,7 ＠＠ timeout->interval_id = event_stream_add_timeout (timeout->next_signal_time); pending_timeout_list = noseeum_cons (op, pending_timeout_list); + fprintf(stderr,"InList %i\n", timeout->interval_id); } return timeout->id; } ＠＠ -1199,6 +1200,7 ＠＠ GCPRO1 (op); /* just in case ... because it's removed from the list for awhile. */ + fprintf(stderr,"Looking up: %i (%i)\n", interval_id, async_p); timeout_list = async_p ? &pending_async_timeout_list : &pending_timeout_list; /* Find the timeout on the list of pending ones. */ Index: event-Xt.c =================================================================== RCS file: /usr/CVSroot/XEmacs/xemacs-20/src/event-Xt.c,v retrieving revision 1.40 diff -u -u -r1.40 event-Xt.c --- event-Xt.c 1998/05/14 04:46:24 1.40 +++ event-Xt.c 1998/06/18 17:15:22 ＠＠ -1677,6 +1677,7 ＠＠ timeout->interval_id = XtAppAddTimeOut (Xt_app_con, milliseconds, Xt_timeout_callback, (XtPointer) timeout); + fprintf(stderr,"Allocated: %i\n",timeout->id); return timeout->id; } ＠＠ -1706,6 +1707,7 ＠＠ */ XtRemoveTimeOut (timeout->interval_id); + fprintf(stderr,"Removed: %i\n",timeout->interval_id); Blocktype_free (the_Xt_timeout_blocktype, timeout); } ＠＠ -1719,6 +1721,7 ＠＠ /* timeout events have nil as channel */ emacs_event->timestamp = 0; /* #### wrong!! */ emacs_event->event.timeout.interval_id = timeout->id; + fprintf(stderr,"Completed: %i\n",timeout->id); Blocktype_free (the_Xt_timeout_blocktype, timeout); }