Domino Server Crash Re6.0.1 help?

os is Aix5.2. the Server Crash at night every day.the NSD file show

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thread 2/3 :: amgr pid=26936, k-id= 68123 , pthr-id=258

stack :: k-state=run, stk max-size=98304, cur-size=26236

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read.read(??, ??, ??) at 0xd01dde08

OSFatalTermination() at 0xd33dc930

ChildCleanup(??, ??, ??, ??) at 0xd33dc6e8

child_died(??, ??, ??) at 0xd33dbf00

select(??, ??, ??, ??, ??) at 0xd0251120

unix_usleep(??) at 0xd26b6b74

TimerTask(??) at 0xd3660dd8

_pthread_body(??) at 0xd0108480

./tmpfiles.18606.scr: 81: warning: Thread is in kernel mode, not all registers can be accessed.

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thread 7/61 :: http pid=31792, k-id= 48769 , pthr-id=1543

stack :: k-state=run, stk max-size=527476, cur-size=2508

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read.read(??, ??, ??) at 0xd01dde08

OSFatalTermination() at 0xd33dc930

fatal_error(??, ??, ??) at 0xd33dba38

.() at 0x0

gcHelper(??) at 0xd4d43c98

xmExecuteThread(0x303d9a14) at 0xd4cc2ca0

threadStart(??) at 0xd4ca6cb8

_start(??) at 0xd4e1bd2c

pth_pthread._pthread_body(??) at 0xd004b328

./tmpfiles.18606.scr: 1271: warning: Thread is in kernel mode, not all registers can be accessed.

why?? help???

thank u.