Try different install media; sounds like that one's scratched (or, if a mounted ISO, corrupt).
And, while you're trying things, some advice...
Don't install SQL Server Enterprise on a Windows 7 machine. No good can come of it.
If you must use Windows 7, use SQL Express. Using SQL Server Enterprise on Windows 7 is going to be a waste of a very expensive license, because the limits of the Windows 7 OS will render the more advanced features of SQL Server Enterprise useless.
Why install a 32 bit version of SQL Server? Unless you have a good reason not to, use the 64 bit version instead.
Don't try to use a Windows 7 OS as a server operating system, because it's not. Use a real server OS instead.
- Things like sparsely documented concurrent connection and user limits will make this a nightmare.