Only pc program work on my mac

[charley0007]

By mean of boot camp, i install vista ultimate on my imac.Everything was working ok. i can bring up either programs by holding down my option key and then choose either pc or mac ox. But now a problem has come up. i can now only boot up the pc program and it does not matter if you use the option key or not. Pc program is all i get. what can i do to get back on my mac ox program?
Yours Truly
Charley0007

 

[r.j.s]

Go to Control Panel ... Startup Disk, and see what your options are ...

Have you made any changes to anything recently?