Vista Boot Manager wont respond to my keyboard

I have dual boot with XP & Vista... Vista is set as the detault OS, so it is
highlighted by default.

However, I can't choose XP using my arrow keys, it doesn't respond to my
keyboard. I can't even press Enter to load Vista immediately, I have to wait
for the countdown to finish to load Vista.

Is it safe to use VistaBootPRO to change my default OS to XP to load XP? Or
does this mean my XP partition is corrupt, useless?

I used Vista Ultimate UPGRADE to do a Clean Install on another partition
(D). XP resides on C partition. Both are on the same hard disk, however.

Help needed, I don't want to completely mess up the system by doing
something stupid.