The reasons for this problem are: software incompatibility, software crash or damage, and network problems.

1. Software Incompatibility: English teaching may be incompatible with the operating system or other software, which makes it unusable.

2. Software crash or damage: Teaching English cannot be used for various reasons, such as server failure, software crash or damage.

3. Network problem: English teaching needs networking to be used. If the network connection is unstable or there is a problem, it may not be available.