You should go to c: and open the boot.ini file (boot.ini is a hidden file) OR go to Start/Run... and type sysdm.cpl .
There you should write this:
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partitiā¦
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows XP" /fastdetect
multi(0)disk(0)rdisk(0)partition(2)\WINNIT="Windows Server" /fastdetect
If that doesn't work, try replacing WINNIT with WINDOWS
PS: First make a backup of your boot.ini file, in case you don't want something messed up
