Addendum to @Sander Mangel's answer as to why they may have been forcibly disabled:
If you inherited the management of this website, the compiler is probably shut off for a good reason, the previous maintainer may have found that it interacts quite foully with an installed third party module and decided to prevent the issue from resurfacing.
Starting with version 1.6, code optimization has rendered the compiler speed gains to be a moot point, better to shut it off and be using
Backup is also known to reset file permissions, causing the website to go down after executing backups with a 500 error when suPHP or WHM/cPanel security settings get violated by a bad Magento developer assumption and may have been disabled for the same reason.
You have to run a script to reset file/folder permissions every time you run the backup when this is encountered. The best cure is to much more speedily back up the database with mySQLdump and the code with tarball scripts instead.