Commercial and proprietary software (CPS), unfortunately, is neither fully reliable nor totally supported and it is easy to see why.
There are tens of thousands of software applications out there and since they come from a whole spectrum of developers, it is very common to get incompatibilities, whether deliberate or not. To rub salt into the wound, there are also a number of programmers out there ready to open the gates of hell and unleash viruses, worms and other malware.
Reliability is also something you cannot take for granted. Even the biggest software vendor Microsoft, which has an army of developers at its disposal, can be painfully slow to release a critical patch to protect its own Internet Explorer browser and even when it does, it may cause havoc.
And of course, EULA (End User License Agreement) restrictions mean that the usage of software is not guaranteed in any way whatsoever. It’s for this reason that nuclear power stations and airplanes are not run by consumer grade (or even business grade) software since it is not deemed reliable enough.
Some may argue that CPS is less reliable and supported because money is, more often than not, the main motivator. But it is much more complex than that.
Because open source is open, it is easier to find errors and to correct them. More eyes looking at the source code means that patches can often be released quicker. If you use Internet Explorer or Lotus Smartsuite, for example, you have no choice but to wait until the vendor gets round to issuing a patch.
Microsoft has been focusing more on reliability lately with very good results, but the fact that CPS is paid for means that proper support is the very least that you should expect.
You can read about the ten other myths of commercial and proprietary software here.