Hi I am having a problem with my PC at home. I uninstalled Zone Alarm (v4.5 I think) and it said it needed to reboot to complete the uninstallation. As soon as the PC rebooted, there was a message saying CheckSum error: CPU settings changed, Defaults loaded. Press Del to enter Setup, save changes, F1 to continue. I know very little about the BIOS settings. I did press Del, but I don't know what would have changed so quit without saving. I pressed F1 to continue and Windows XP loaded fine and I installed the newer version of Zone Alarm (v5.1 I think). Again it said it needed to reboot to complete the installation. PC shut down, but it didn't reboot. Now nothing happens when I switch on. My flatscreen monitor is showing the message: No Video Input. I have tried another monitor and that didn't work either. I have opened the case and the fan is working, a light comes on on the motherboard (next to the memory), both CD and DVD-ROM drives are working and the hard drive light on the front flashes. The motherboard (a DFI Infinity model, 865PE I think), power unit, processor (P4 2.8 GHz), 140GB hard drive and video card (Radeon 9600) were all installed last April so I am hoping nothing needs replacing. Nothing is overclocked. I have been using Zone Alarm as my firewall, I have AVG Antivirus and run Ad-aware scans regularly. I also have Spyware Blaster installed. I have had a quick look on the net and it seems the problem could be caused by the battery, motherboard problems or a virus. I have never had this error occur before and with nothing appearing on the screen I cannot enter the BIOS to change any settings. Do you have any idea what the problem is and how it can be fixed? Thanks for any help.

HI Find the Clear Cmos jumpers on the board, if it has one. Refer to your MOBO manual for instructions. Disconect from the mains power. Throw the Clar cmos Jumper as instructed. Than remove the battery for about 5 minutes just for good measure. This should reset the bios back to fail safe deafults. Replace the batery and set the jumper back to normal position. Try and boot the comp. If it boots, jump back inot the bios and set it up the way it should be. You will need to set the clock up again. If the comp boots to windows ok, shut it down again, remove the power cable for about 5 minustes only, and than jump back inot the bios and see if the Clock has reset to zero again. If it has than the battery is dead, if not than something else may have upset it. In the mean time have a look and see if there are any latest bios updates at the manufacturers web site for your board. refer to you MOBO manual. Why ZA would have anything to do with this is a bit strange. Hope that helps Regards IF IT AINT BROKE, DONT FIX IT

After resetting the BIOS setting by pulling the battery, and then getting into the CMOS Setup, look for the "Load Defaults" option. Select it and Save the settings when you exit.

try cleaning the ram contacts

Thanks for all your help. I removed the battery and the PC booted up fine without it; replaced the battery and again it would not boot up. I bought a new battery at the weekend and the PC booted up fine. I loaded optimised defaults in the BIOS and have not had any problems since. It looks like it was a dead/faulty battery.