realyifei,

Thank you for using Dell's Community Forum.

I would first, take your system off the docking station if you have one. Then take out all peripherals like printers, scanners, mice, keyboards, pc cards, and any other 3rd party devices you have added. Also, take out the battery and disconnect the ac adaptor and wait for 2min. then add only the ac adaptor back on, and try to boot.

Thanks for you help. I have tried all these steps you suggested, unfortunately, which did not fix the problem. It still hangs at the same point (as progress bar reaches 80-90%). If I took off one memory chip (I have two), it DID report something like "Invalid configuration infor, please run setup" before it got stuck, but after the power are turned on again, it just hangs as usual.

I am just wondering if there is a way I can either flash the BIOS or replace it by a new BIOS chip.   

realyifei,

You should try running the Dell diagnostic program.
You run diagnostics to make sure that there is not an actual hardware problem. To do this, put your System Utilities CDROM that came with your computer. To launch the diagnostics, insert that CDROM into your computer and then restart your computer. If the computer does not automatically boot from the CDROM you may need to change the BOOT FIRST device in the BIOS.

 I can't run diagnostics because the computer hangs before booting from cd-rom. It looks like running a infinite loop somewhere in bios, this is the reason I would like to try to replace the bios, either the chip itself or flash a new BIOS somehow. 

realyifei,

In that case, you can contact us in regards to getting your motherboard replaced.