The scenario:
We tried to install WinXp in it but we failed. So we installed MacOs in it again. Before it came to completion, the installation freezes. We tried to eject the MacOs installation cd but we it didnt work. We poked it but still no effect. The pc displays only a gray background with a folder icon and a "?" inside it.

what seems to be the problem? how can i fix it? I really need your help guys ASAP... thanks in advance! Happy Holidays!

PS: if you want you can im me in YM. my YMid is: isuraeru02

You will never get Windows XP to install on the iMac it was never made to go on the iMac.

In regards to the Mac OS disk not working, what version of the Mac OS are you trying to install? If you want you can try holding down the C key on your keyboard while the machine turns on. That will boot the machine from the CD drive where you can attempt a reinstall.

If that doesn't work I refer you to the apple website

For Tray-loading iMac

and Slot-loading iMac