No bootup; clock loses time

I have a Dell Inspiron 1526 laptop running Vista SP2.  Recently two problems have developed. First, the laptop frequently fails to boot up.  When I push the power buttom, I see a light or two, but the Dell BIOS screen never appears.  I wait and wait and then finally power down by holding the power button for several seconds.  I have found that disconnecting the battery and power supply and holding down the power button for 30 seconds seems to help on the next attempt to boot up, but not always.  I usually can finally get it to boot up, and I now tend to leave it on for several days at a time to avoid this problem.  At about the same time, the clock began losing time -- like 2 years.  Instead of Dec 2011, it would be Dec 2009.  I have reset the clock due to this problem several times.  Maybe the two issues are related?? BTW, I reloaded VISTA and SP2 from the recovery disk and updates, but problem still persists.   Any suggestions?   Thanks,   Mike in VA.

http://support.dell.com/support/edocs/systems/ins1526/en/SM/coinbatt.htm#wp1179949

Replace your coin-cell battery detailed above...