Win2000 selection still on at bootup

I have Win98 on a drive that I used as a slave with Win2000 on the master for a dual boot system. When I tried using the W98 drive as a single the dual selection (win2000 or Win98) still comes up at bootup. How can I remove the reference to Win2000 (boot.ini,msdos.sys or some other .ini or .sys file perhaps)? The drive will still boot to Win98, if I select it before it times out, with no problem.