It is not widely known how many issues the industry faces. Even the most effective antivirus software can encounter issues. Some are minor and may easily be dealt with, while others are more serious.
One of the main problems is that virus signatures are not enough to defend against a wide range of threats. Each time a new virus is discovered, it takes a while before antivirus companies are able to create and release new anti-virus updates. They have to wait until the virus is identified by their products and then sent to be analysed.
The virus will spread and dozens or even hundreds of computers are likely to be infected. It could also spread to other networks. To be effective, anti-virus software needs to be able to detect and stop these infections quickly. This means that behaviour blockers or heuristic analysers are more effective than signature detection.
Another problem is that the incompatibility of different antivirus programs is quite frequent. Although the majority of antivirus software developers place much importance on the creation of high-quality products and pay a lot of attention to fixing bugs, the reality is that occasionally multiple antivirus programs can create conflicts.