At first glance, the name offers breadcrumbs. "FS" typically stands for "File System" or "F-Secure." "MainUI" suggests a user interface component. A quick search of reputable process databases reveals the truth: fsmainui.exe is a legitimate signed binary associated with (now WithSecure) antivirus and security suites. Specifically, it is the Main User Interface handler for the F-Secure Internet Security and PSB (Protection Service for Business) suites.
Typically a corrupted F-Secure installation, damaged Windows system files, or a conflict with another application. fsmainui.exe
If you do not use F-Secure, uninstall the program properly, and the file will disappear. If the file appears outside the F-Secure folder, scan it immediately. At first glance, the name offers breadcrumbs
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