It's widely agreed that Linux is very stable and Windows is unstable. Although the situation is improving with each new version, it's rare for Windows users to see a month, week, or even day without a crash or a forced reboot. Yet Linux has been known to quite literally keep running for years. Why this is so comes down to differences in approaches to producing software.
Windows is closed source, which is to say that only Microsoft employees and a select group of individuals around the world can see its source code (the original listing created by the programmers). This means that when a serious bug arises and causes the operating system to become unstable, only Microsoft engineers can diagnose the cause of the problem, and only they can fix it. The world is at their mercy. If they don't consider the bug serious enough to be fixed immediately, you're out of luck and will need to wait until the next major update is released.
Linux is completely the opposite. The source code is always open and available for anyone to see. The end result of this is that if a bug is identified, many people around the world attempt to diagnose the cause. What they discover is then fed back to the original programmer, who is able to fix the bug very quickly. A new version of the program is then made available immediately, and everyone can download and use it (although many people wait for the release of a full update—a so-called point release).
However, none of this is to say that Linux is perfect. It rains even in paradise, and from time to time, you might run into problems with your Linux setup. Programs will occasionally crash, and you might need to do a little problem solving. Fortunately, the creators of Linux realized that things go wrong and built in a variety of tools to help.
Windows works on the basis of hardware manufacturers producing drivers for the hardware you use on your system. While this means that most new hardware is instantly able to work with Windows, it also creates many problems. Few drivers are bug-free, and if the hardware in question is a fundamental part of the system (such as the graphics card or a RAID controller), its driver can crash the entire system. If this happens, you must wait for the manufacturer to release a new version of the driver, which can take weeks or months.
It is possible to use third-party driver software with SUSE Linux, but it's not very common. Instead, support for most hardware is built into the SUSE Linux kernel. Sometimes, this is provided by the manufacturers of the hardware, although most of the time it's written by one of the core kernel team who reverse-engineers the hardware. This means that the Linux developer attempts to find out how the hardware works and produces software based on these discoveries.
If the manufacturer does provide driver software, the open-source nature of Linux means that the code can be inspected before it's allowed to be a part of the kernel program. This means that bugs have a much greater chance of being unearthed.