Few people realize how many problems the industry has to face. Even the most reliable antivirus software can encounter issues. Some are minor and may easily be dealt with, while others are more serious.
One of the main issues is that virus-signature protection doesn’t cover a broad range of threats. Whenever new viruses appear they take a while before the antivirus companies are able to create and release new anti-virus updates. This is because they need to wait until their products are able to detect the virus and then send the virus to be examined.
The virus can spread and dozens or even hundreds of computers could be infected. It could also spread to other networks. To be efficient, anti-virus software has to be able to identify and block these viruses quickly. This means that heuristic or behavior analysers are more effective than simple signature detection.
Incompatibility is a different issue. While the majority of antivirus software makers focus on creating quality products and removing bugs it is true that different antivirus programs can occasionally create conflicts.