i had have this problem in the past... and this is what i think... [dont hold me to any of these]...
well, the reason that appears is that you DO have 2 systems set up on your pc... to remove it.. go to start.run.msconfig. then go to the BOOT.INI tab and look under "[operating systems]" .. the BOOT.INI is a text file you can view with Notepad. you have to edit/delete the other system...im not sure how.. forgot.. it should show you the two systems you have set up.. there is a way to remove it.. im not 100% sure.. but remember which system that works and set that one as default on the button below it.. reboot.. if it still shows.....go back to msconfig and set the timeout to 0 as everyone has recommended as thats all i know.. lol. if i remember..i'll get bakk with u