There is no such thing as an error-free computer. While the Mac OS, which is based on BSD Linux, is quite robust, even it can have problems from time to time. When things start to go wrong on your Mac there are some simple tasks that should bring it back to health.
There are steps to follow to help in solving most Mac software, and even hardware, problems. If you have a program that seems to be frozen or just lost its way, meaning you have an ever spinning colored beach ball, then you may want to try to force quit the offending program. Hitting Command-Option-ESC on the keyboard should bring up the force quit dialog box. If it doesn't, then click on the desktop to switch to the Finder. Now look under the Apple menu in the upper left corner and select Force Quit. In the Force Quit dialog box you should see a list of all the applications currently running. Any application that is having a problem will be listed in red along with 'not responding' in parentheses. Click on the name of the program to highlight it and click on Force Quit. Remember that this is a last ditch effort and any data that hasn't been saved will be lost.
If you continue to have OS or application problems then a reboot may be in order. Just choose Restart under the Apple menu in the upper left corner. A restart quits all programs and clears out anything stuck so you can start fresh. If the Mac sits there trying to shut down and seems stuck, then wait as long as you can, at least five minutes, then if it still isn't shutting down, press and hold the power button in for about seven seconds. This will force the Mac to power off.
Powering off is another way to fix problems. If your Mac is having problems communicating with printers, scanners, networks, then a reboot may not be enough. The USB bus, Ethernet port, or Airport card can get stuck and only a true shut down can reset it. If your printer or scanner is having problems communicating you may need to power them off also.
If you use your Mac for work, or for all the other important stuff in your life (financial records, digital photos/video, music, etc.) then I would recommend getting a good disk utility program. Diskwarrior from Alsoft is the best tool for fixing damaged disk directories. For all around Mac fixing and maintenance, there is Tech Tool Pro from MicroMat.
Either of these utilities can save your Mac from expensive repair shop visits. Diskwarrior repairs hard drive directories. This is where the Mac OS stores the list of all the files on the hard drive and where it is located. If this gets damaged or corrupted, a Mac can start to behave badly and you will lose data. Tech Tool Pro has this same function, plus it adds system checks for RAM, Video, drive defragging, and even data recovery.
To use either of these tools, insert the disk into your Mac and reboot. As soon as the Mac restarts, hold down the C key. This will force it to boot from the CD drive instead of the hard drive. Since an optical drive is quite a bit slower than a hard drive, it will take longer for it to startup. Booting from the utility disk allows the software to make repairs to the hard drive, which it cannot do if it is the boot drive.
If you are having problems now and can't wait to purchase one of these programs, you can try the built in Apple disk utility program. In OS X it can be found in the Applications folder inside the Utilities folder. It is simply called Disk Utility. This is the program used to make disk images of CDs and DVDs, partition/format new hard drives, and to test and repair hard drives.
When you start Disk Utility you will see a list of drives and drive images in the left side column. Click once on the Mac boot drive and you will see lots of info about the drive (capacity, available space, number of files, etc.). In the main panel there are tab buttons at the top. The first button is First Aid. With the drive selected, click on the First Aid tab. Since you cannot repair a boot drive, the only selection that is active is the 'repair permissions' utility. This is an important part of your Mac's health. You should do this every few months, or after you have installed several new programs. It is also a good thing to do before you do any type of drive cloning operation (i.e. backing up with software like Super Duper or Carbon Copy Cloner two great free utilities).
To run the Apple Disk Utility and use the repair function, you need to boot your Mac from the OS disk. This is the same disk you use to reinstall OS X. Don't go through the install process, this could wipe out all your data, just look under the Tools menu and you will find Disk Utility. Now you can select your hard drive and the Repair option is no longer grayed out, but the Repair Permissions is. Since this is not a boot disk, permissions are ignored.
Another important part of keeping you Mac fit is to keep the OS updated. In the System Preferences you will find the Software Update icon. Here you should tell it to automatically check for system updates. Apple quite regularly updates Mac OS X and other programs, like iTunes, Quicktime, etc. The most important updates are the security updates. These are fixes to the OS that help keep your Mac safe and secure while surfing on the Internet.
While no computer is safe from crashes, freeze ups, and lost data, a Mac with OS X is a very stable system. Plus, a Mac is much safer to use on the Internet without having to worry about the tens of thousands of Spyware traps that Windows users have to deal with everyday. Don't brag too loudly though, the Mac does have security holes, like all modern operating systems, and while there are no real virus threats out there today, who knows what tomorrow will bring.
Regular maintenance is an important part of keeping your Mac up and running. Disk utilities are just a part of a regular plan. Keeping your data backed up is another very important piece of the puzzle. Having tools like Diskwarrior, TechTool Pro, and knowing how to fix the occasional software/hardware mishaps is an important part of keeping your Mac running smooth.