2006 IMAC 20 incher freezes intermittently and says files are corrupted and need to reinstall original owner disc that came with imac. I have upgraded it to leopard, etc and upon looking up my serial number @Apple - it states Original OS: 10.4.4 or 10.4.6 Tiger. I don't have such. Do I need to buy one? or Ebay 2nd hand OS X Disc work? Or ...?
If you are in the US call Apple Customer Support 1-800-767-2775, provide the Serial Number and specifications of the Mac, and for a reasonable fee, they will supply a replacement set of system discs (if available).
The discs will be for the original version of the OS that was pre-installed when the Mac was manufactured.