When using Software Update, it prompts you to restart your computer. After doing so, it installs the update which then freezes. You have to turn off the computer forcefully.
- Double click on your main hard drive (usually Macintosh HD).
- Go to the Library folder.
- Go to the Updates folder.
- Delete everything in the folder.
- Click the Apple in the top left of the screen, then click Software Update.
Then try installing updates again.