[newbie] prob w/ grub window

[Tim]

I had the 7.1 linux-mandrake successfully installed with dual boot, for
linux/windows. then I tried configuring something diff. and messed it up. Now,
I get the grub window, but when I try to select windows to boot,  it will not
boot windows, and after the timer loads linux. What do I need to change and
where, to be able to dual boot again?. thanks.