On my machine (Windows 7, 64 Bit) the TrustedInstaller.EXE is permanently active. The amount of used CPU changes permanently. 2 seconds 0 % then up to 50% (I have a dual core) for a second then down to 0. Rebooting the machine did not help. Also a complete Virus scan was negative. I have monitored the process with the Process Explorer tool. I can see that the process always access the same Registry key when it gets active. The key is HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Component Based Servicing\PackageDetect\Microsoft-Windows-IIS-WebServer-AddOn-2-Package~31bf3856ad364e35~amd64~~0.0.0.

Trusted Installer Notes

TrustedInstaller is used by a service called “Windows Module Installer” which is used to install Windows 7 system modules. The system modules include Windows Update and Automatic Updates which automatically scans your system to check for any new updates and hotfixes available. So when scheduled Windows Update is performing its update scan or check on your system, the TrustedInstaller.exe process increases the CPU usage.

The simplest resolution for the TrustedInstaller high CPU usage problem is to wait for a while for the TrustedInstaller.exe to complete its job. Once it finishes running the tasks, the CPU usage rate will return to normal.