i just installed a 5.1/4 floppy drive to try and use some old dos programs i keep getting i/o device error message what is my problem?

you have to change your BIOS setting for the 51/4" floppy to work properly and/or if your BIOS automatically accepts the latger floppy then you will have to install the correct drivers for it.

There might be a compatability issue as well.