Hi Sweetie, First if the CMOS battery were dieing you would notice via your CLOCK and DATE down at the bottom right hand corner, they would ALWAYS be slow, or incorrect everytime you started up your computer. (I just had to replace my mothers)
Second, Are you using the PHYSICAL POWER bottom to turn it off? Becasue you should NEVER use it except in Emergencies. Press and Hold it down till it shuts down about 5 to 8 seconds.
I do not know your OS, I am assuming its XP/Vista/7?
Third, Your POWER OPTIONS may have been changed by a Virus, Trojan or Worm. Malware gets in there and turns you system into a BOTNET. (not good!)
Forth, I NEVER shut my computer off, I just unplug the computer connection cable and it eventually goes to STAND BY. then when i need it i plug the cable in and press ENTER and I am now back up and running and I always open the case and direct a little fan into it to keep it cool.
I am going to include the Link about BOTNETS.
and Fifth, email me if none of these help. or just email me anyway.
Sorry I have not answered before but I have been working on the the house and playing w/that stupid Facebook.
Hope any of these help.