4GL debugger "use" command causing coredump

Yet another obscure weirdness here: HP-UX11i, IDS9.30HC5, R4GL 7,20UD8, IDB (debugger) 7.20UD8 Our 4GLs all call general 4gl library functions which reside in a different path; so to debug them we need to specify the "use <some other path>" command under the debugger. One of our libraries is now causing a coredump ("13193: Memory fault(coredump)"), when we try to run the debugger, at the point of issuing the "use" command (and we have to issue "stty sane" to get command line back), and we can't see why. The code works perfectly well under the runner, and not all programs that use the library in question coredump when we debug them and issue the same "use" command. It happens with a simple "use" and also the "use = " form. Anyone have any clues? Perplexed of Kent.