imac freezes after boot up-mouse moves but no response from icons

[colivero]

I can log in barely And the mouse movement is great but I don't get a response from any selected icon.System OS X with Snow.

 

[Satcomer]

Boot with your original system disk and use the install disk to get to Disk utility and use that to repair your OS X installation. If you can't do that follow the steps in the Apple document Resolve startup issues and perform disk maintenance with Disk Utility and fsck.

IMHO your hard drive installation is messed up. Good Luck.