Messages "Failed to update jar archive file ..." at Jonas STart

Hello,

I would like to submit to you the following problem which occurs with 
Jonas 4.9.2 on Windows 2008:

When Jonas starts, I get once or more the following message, which is 
produced by GeniC:

*Failed to update jar archive file 
'C:\Evidian\J2ee\Jonas\OM_base\work\apps\omjonas\om_monitor_srv_2010.12.14-20.01.43\mo_ejb_action.jar'*

When I check the directory 
C:\Evidian\J2ee\Jonas\OM_base\work\apps\omjonas\om_monitor_srv_2010.12.14-20.01.43,

I see that both files mo_ejb_action.jar and  mo_ejb_action.jar.tmp exist.

Le fichier mo_ejb_action.jar.tmp contient les stubs et les skeletons.

It looks as though mo_ejb_action.jar has not been deleted, which 
prevents file mo_ejb_action.jar.tmp to be renamed.

  This problem does not occur every time n'est : on 13 GeniC executions 
, some succeed, others fail.
If I launch Jonas several times, I can see that the problem does not 
always occur with the same jars

I tried with JDK SUN 1.5.0_09, 1.6.0_16 and JRockit 1.6.0. With both 
these JDK, I have the problem. Moreover, it seems that the problem 
always appear with JRockit.

Does someone have an idea about this problem?

Thanks,

François Urbain