Phenomenon:
1. A few minutes after the machine starts running, svchost.exe will take up 100% of the system CPU resources.
2. Unplugging the network cable fixes the issue temporarily, but after reconnecting to the internet, svchost.exe soon takes up 99% of the CPU resources again.
Solution:
Assuming you have already used free antivirus software to rule out viruses and anti-spyware tools to exclude the influence of malicious software:
Clear all files in the C:\WINDOWS\SoftwareDistribution directory and restart the machine. If the machine prompts that files are in use ("Automatic Updates" service is running) and you cannot delete the corresponding directory, then open Control Panel ==> Administrative Tools ==> Services, find "Automatic Updates", and set it to manual startup. Restart the machine and then delete C:\WINDOWS\SoftwareDistribution. The problem will be resolved. Then open Control Panel ==> Administrative Tools ==> Services again, find "Automatic Updates", restore it to automatic startup, and restart.
Note: After restarting, it's best to perform a system update in a location with good internet connectivity to ensure the system completes an automatic update successfully. (via)