Hi WoodyZ,
Thanks for the advice and I've already understood your mention. But I own some another Clone OSs (e.g. CentOS 6.3 and Fedora 17)
on the similar environmental machines and they have had no problem until now. I don't know the reason at all. 
BTY, I installed the latest Kernel last night again which was released several days ago on Scientific and no change was found...
At that time, I found the following outputs in vmware.log:
2012-12-21T02:26:26.250+09:00| vmx| I120: VMIOP: Exit
2012-12-21T02:26:26.252+09:00| vmx| I120: Vix: [5823 mainDispatch.c:859]: VMAutomation_LateShutdown()
2012-12-21T02:26:26.252+09:00| vmx| I120: Vix: [5823 mainDispatch.c:809]: VMAutomationCloseListenerSocket. Closing listener socket.
2012-12-21T02:26:26.254+09:00| vmx| I120: Flushing VMX VMDB connections
2012-12-21T02:26:26.254+09:00| vmx| I120: VmdbDbRemoveCnx: Removing Cnx from Db for '/db/connection/#1/'
2012-12-21T02:26:26.254+09:00| vmx| I120: VmdbCnxDisconnect: Disconnect: closed pipe for pub cnx '/db/connection/#1/' (0)
2012-12-21T02:26:26.260+09:00| vmx| I120: VMX exit (0).
2012-12-21T02:26:26.260+09:00| vmx| I120: AIOMGR-S : stat o=3 r=18 w=0 i=0 br=167424 bw=0
2012-12-21T02:26:26.260+09:00| vmx| I120: OBJLIB-LIB : ObjLib cleanup done.
2012-12-21T02:26:26.260+09:00| vmx| I120: FileTrack_Exit: done
The VM and OS was forced to reboot while outputting the above content. It apparently looked like freezed then.
Regards,
takao46