Why does my dell inspiron 1525 laptop go to boot manager page before it loads th

how do i get my dell inspiron 1525 to not go to the boot manager screen befoe it selects the operating system? it shows two f the same os's but the first oneis all messed up ad does not have drivers for the ethernet or the wireless car or the drivers for the printer and the wireless router and my bluray player is not reconized if i select the first operating system so how do i get rid of that bad OS? i think thats why it keeps popping up and no going directly to the os because i tried to reload an old restore and it was too old and did not have service pack 2 on it so none of my suff worked with that so i ha to rstoreit all from another computer. why cant i get that to stoppopping up and how to get rid of the bad OS?