Yes thats a common problem when using the GUI install. I assume you are using the Backtrack HD front end installer.  It doesnt copy the boot folder correctly. If you still want to use the GUI installer, follow this:
http://www.ethicalhacker.net/component/option,com_smf/Itemid,54/topic,1433.0/

Just remember to leave the source field blank or you can simply enter /. Dont enter /boot because it wont copy.  I have never had a problem installing this way and I have done it on a variety of laptops and desktops.