Try to install it using compatibility mode, that game is not compatible with Win 7 http://www.microsoft.com/windows/compatibility/Windows-7/en-us/Details.aspx?type=Software&p=Grand%20Theft%20Auto%3A%20San%20Andreas&v=Take-Two%20Interactive&uid=2&pf=0&pi=3&c=PC%20Gaming&sc=Role%20Playing&os=32-bit..