hmm interesting. so i'd say when u boot up the computer you get a black screen prompting you to select your operating system?
If so and dont need all 3 you can go the system properties/advanced/startup and recovery settings.
There will be something that says "To edit the startup options file manually, click edit."
When u click on edit on the right-side it should open a notepad.
I think yours might show like this...
multi(0)disk(0)rdisk(0)partition(1)blah blah blah/fastdetect
multi(0)disk(0)rdisk(0)partition(2)blah blah blah/fastdetect
multi(0)disk(0)rdisk(0)partition(3)blah blah blah/fastdetect
multi(0)disk(0)rdisk(0)partition(4)blah blah blah/fastdetect
or something of that nature. They should end with "/fastdetect"
all u simply do is delete the whole line of the partition for example u shouldnt need(2,3,4).
make sure u have notepad maximized.Sounds easy BUT be VERY careful.U can screw up teh bootloader. Once done correctly, simply save and exit. Reboot.