Hi,Im putting this problem in for my son as we dont know where to turn to next.He had an MSI mobo 745 ultra with 512 DDR that suddenly started to tell him that his CMOS settings were wrong or that the battery was low.Put in correct CMOS setting only to have same CMOS settings wrong on next boot up Also fitted two new batterys.Then it became a problem to start the computer also when after setting CMOS & F10 to save settings the computyer would not re boot.So bought new mobo (ASUS a7V8X)had problems in that when setting bios againn it would not reboot had to switch off & restart.We then put in XP disc at boot & reloaded windows & it now starts up (but reset button does not work tried switching connections no difference)Also now when it starts it goes into the advanced page of bios & asaks if he wants to keep these settings.On ther CPU speed he only has Manual-650 MHz-867MHz-1083MHz & 1300 MHZ as options.Goes to Manual sets CPU Multiplyer to 12.5 x & CPU FReq to 133/33 to get 1667 MHZ.He has AMD xp 2000+ cpu.Why tho does it keep boot to this page on start.Sorry the this is so long but only way I could detail the events

See if Asus have a BIOS-update for that mobo and read first what that BIOS has for new items.
Also, what is the brand/model/output of your power supply? That might be on the weak side and could influence proper running.