Problems with finalising Mac OS 10.6 instalation

Hello,

I purchased iMac 24 EMC 1211 for my collection and it worked well for weeks till the moment systems sometimes started to crash Finder and recovering it immediately. I decided to install Fresh copy of MacOS 10.6 to a new SSD 256Gb drive several times from different sources (Also I exchanged RAM models) so we can exclude SSD and RAM problems. After installing system new problem appeared: Introduction Video started to play and during registration process when I press next at the end video started to play over and over again without letting me to finalise the registration. At the same time I was able to boot from old SSD (connected to USB drive)

For your concern:

1. I tried to install MacOs 10.6 several times from different sources (DVD, external HDD) and the same problem with Playing introduction video over and over again persist.

2. I exchanged RAM modules and SSD drive, so we can exclude totally issue with SSD and RAM

I would really appreciate for any comment and if someone met the kind of problem with playing introduction Video without a chance to complete the installation process. or why Finder crashing and recovering Crashing and recovering without rebooting system.

Is this some kind of exotic problem with motherboard and video card?