macos - Is there a way to restore to previous version in Mac OS X after installing the update?

In my Mac OSX I recently updated my Mac from 10.6.5 to 10.6.6.

After I installed the 10.6.6 version, I get error in Finder as below:

The application Finder can't be opened

Just around a minute after restarting my Mac everytime I get the error from Finder and then everthing stops working.

I have lots of important data in my Mac but now I cant take a backup of it as Finder stops working.

So, Is there a way in Mac where I can revert back to 10.6.5 version?

What are my options?

Please Help and Suggest

Thanks

Answer

There's no way to "downgrade" to an earlier version.

Install a full 10.6.x from DVD and use the 10.6.5 combo updater afterwards.