wow,, sorry to bother you guys, little more update.
Last night , the system froze while I was watching something. exactly at around 11. just now I noticed there is a error in my obiters log.
Error log
Device OnScreen Orbiter, # 21
Device Template OnScreen Orbiter, device category Standard Orbiter, manufacturer Pluto.
01 07/21/10 22:01:55.059 Orbiter::CMD_Goto_DesignObj m_pScreenHistory_Current while doing the object offscreen <0xb5292b90>
This matches exact time it froze yesterday. Does it tell any information?