System clock changes automatically by 1 hair daily.. Virus problem ?

hi,,
the time in my system clock automatically changes and gets back by 1 hour daily when i work for a while. is this due to any virus or something else??please give me the solution that it remain unchanged after setting it once.
if it is some virus then give me the name of it or the way to remove it,,???

Just Change CMOS Battery of your system this solve your issue.

CR2032

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