LAN ethernet drivers uinstall automatically on restart

Hello everyone,I am new here
I have purchased a new pc yesterday only and put windows 7 ultimate 64 bit
the problem i am facing is that every time i restart my pc the LAN (Ethernet) drivers uinstall and it shows red cross on network icon on system tray and when i see in manage it shows that yellow sign of driver problem and when i click on update it says drivers are up to date, i had installed kaspersky antivirus, earlier i thought teh problem was because of that maybe it was blocking it but same problem even after installing kaspersky now i think maybe some other firewall is causing the problem or there is compatibility problem of the drivers with my operating system,please help me.

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