I have twicely successfully install my sims2 game from the disk i am talking about now.
2 days ago my dad reinstalled Windows - and did it in some wrong way because we keep finding new problems.
Now I can't istall sims2 games from my disk.
Firstly it gives a message about some errors in Memory Process Reading - or staff like that i m not so sure n a name.
Than at some point it tell about error with Sims2NL and specifies the folder. I click - ok and it keeps installing the game.
Then it informs me that Sims5.exe (which is Pets ) is not a Win32 applicatio - what does it mean??? then it says: can't execute/perform an exterier command
I am sorry for a wrong translation cause i'm translating from russian guessing how can it sound properly in English
What i want ti know - is that my hard disk or a Sims2 dvd problem?

Sounds like either your DVD may be dirty- or else your DVD drive is faulty. Can you install any other games okay? Try cleaning the disc:
http://www.modthesims2.com/article.php?t=82492
http://support.microsoft.com/kb/315589