Help! Can not exit ncsim!

[lioncrude]

Dear all

I met a problem during exiting ncsim .The version of ncsim that i used is ISU5.4.
At the end of log file, it show the following error information:
/**********************************/
ncsim> exit
ncsim: *internal* (genuine access violation (0-c14254e:2)).
Observed simulation time : 5125 NS + 2
Please contact Cadence Design Systems about this problem
and provide enough information to help us reproduce it.
ncsim: *internal* (NO ERROR for error code 0).
Observed simulation time : 5125 NS + 2
....
/***********************************/
I never come with this problem before ,until i added coverage commands . My execution command is :
/**************/
ncverilog +access+r +nccoverage+all +nccovfile+.\cov_config.fc +tcl+.\cov_test.tcl sim.v +libext+.v -y ......
/**************/
The cov_config.fc is :
/****************/
set_glitch_strobe 100ps
set_hit_count_limit 4
set_implicit_block_scoring -on -both *
set_assign_scoring
set_instance_context sim.TopLevel_0
select_coverage -block -module *
select_coverage -block -expr -instance *...
deselect_coverage -be -module RAM_12288x16
deselect_coverage -be -module RAM_4096x16
deselect_coverage -be -instance sim.TopLevel_0.SBRAM
deselect_coverage -be -instance sim.TopLevel_0 .. .. .BIST_0
/************************/
The cov_test.tcl is
/***************************************/
coverage -setup
coverage -code
run
exit
/**************************************/
What`s wrong with my setting? Thanks a lot if you can give me a hand.

Lion