Proplem with my computer after changing the Cmos battery?

I had the cmos checksum error so i changed the battery , after that i started the computer , windows couldnt start and gave an error message that a system file is missing , i tried rebooting and replacing the battery but the computer starts with display proplems , the words at the black screen at start are not displayed properly and i cant even see the settings menu which have the Bios settings , can anyone tell me what the problem is ? and how to fix it ? thank you in advance.|||Check out this


http://www.pcguide.com/ts/x/comp/mbsys/b鈥?/a>|||While PC is off, take out the RAM chip(s). Rub a soft rubber eraser on the golden contact points. Reinsert the chip(s) properly and turn on the PC.|||The check sum error is a MEMORY error and has nothing to do with the mobo battery. You have a bad memory stick.