Sir,

I have a problem with my system .Actually it's clock is getting reset each time when switch off it and then switch off the ups if i don't switch of the ups then it continues to work but if i switch it off then it's gone.Each time it is resting to 29-7-2005 and 12 am i'm geting problem when i use firefox regarding security certificate which depends on system clock help me

This is a sure sign that the onboard battery is about to run out of power. Replace the battery, reset the tme data and all should be back to normal.

Sir
Can i replace it directly

sure...
What kind of computer do you have! Make and Model numbers?????