problem with iphoto

[purplephoenix]

Hi, we have recently purchased an imac and just trying to get to grips with it, last week I or rather my husband uploaded some photos, it worked okay and we could view them, however the iphoto icon now has a no entry sign on it and if i select it a notice coming up says the application iphoto can't open as it may be damaged or incomplete. I can view the photos on front row which wasn't originally on the screen. I would like to use iphoto and wonder if anyone is able to tell me the problem.

Thanks

Hazel