Seems to be general problem. You have not mentioned that what particular error u r facing. May I know that error details. And before you put Redhat DVD make sure that your first boot device is cdrom. Another things is that your workstation should have non dos partition. Then only u r able to install Redhat. So my concern is that just boot windows. Right click on the my computer-> go to manage->select disk management. Now see the entire hard disk partition type.
Best Regards