My destop computer start its own

Hello,
my computer start its own when the time i flug AVR of it ..and stack only in windows , it doesnt go main destop
and i notice the time and date change set in default every time..i reformated it but it still the same..i look also in the ON switch its not grounded or broke..what could be the problem...i suspected is maybe the the battery of the board or the power supply plzzz help me of my problem..it is sumsung board intel processor p4 512 mem..
email me in ryan_r_rivera@yahoo.com