MBP won't boot to OSX?

I'm running a C2D MBP... with boot camp... after booting to XP then back again (whic hi have done fine in the past) my OSX won't complete loading. Even when choosing option key to boot Mac OS. I have that grey screen with an apple logo with a spinning icon below it but no further...


What should I try first?

try booting in safe mode by holding shift during bootup and see if that even works
if not, you may have to reformat

I booted using apple key +s then ran /sbin/fsck -f . that seemed to correct the disk (due to harsh power off?) and allow me to boot. so far soo good!

In windows xp go into control panel
and under the boot disk target it to os X
you could also try and restore youre mac through the restore disks
=]

nah man that disk check command worked fine ....but thanks!