I am pretty sure, ur computer doesn’t fulfill minimum configuration to load Windows Server 2008. U asked the almost same questions earlier. Carlosdl already notified <a href=”http://itknowledgeexchange.techtarget.com/itanswers/dell-rack-server/”>here</a>
Windows Server 2008 is completely different architecture from Windows Server 2003. So, at first check ur HW configuration very cautiously before install Windows Server 2008. After that check the media, from where u want to install the OS. check the CD/DVD drive and if possible update with firmware. CMOS battery on the motherboard that provides power to the Complementary Metal Oxide Semiconductor (CMOS) chip, even while the computer is turned off. This chip contains information about the system configuration like hard disk type, date / time and the order in which the computer will look for bootable disks i.e. boot sequence. The CMOS battery allows the CMOS to preserve these settings. If u r facing CMOS battery related problem, please change this with new one. Battery is cheap and u can find it from any computer shop (u can take help from a HW engineer). Inside the CPU, there is a lithium battery which may change to solve ur problem.