core dumped

[CWen56]

Hi
    I don't what's happening on my Redhat 6.0. When I install
ns-src-2.1b6-curren, nothing could pass the validation. After changing
installing ns-allinone-2.1b6, all tests pass. but nomatter what i run
simulations like wireless.tcl,wireless-test.tcl and all the successful
simulations before, it just core dumped.
    May someone share his experience? or give me a hint about that.
because i didn't find the solution in FAQ. thanks
regards
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[root@atmlab03 ex]# ns wireless-test.tcl
Segmentation fault (core dumped)