There is a discussion about this with 72 answers at http://forums.cnet.com/7723-10149_102-113089/7-8-05-stop-chkdsk-from-running-during-start-up/?tag=rb_content;contentMain
I can bet you don't have a boot DVD so let's get one.
Now you are ready. Test that boot CD/DVD and use the commands to end this.
I have been stuck at stage 5 of 5 (67%) on a chkdsk /r for hours over 24. I can not stop the chkdsk by pressing any key when I reboot. How do I get it to stop? Running Windows Vista on a Toshiba laptop