Startup.cpl is considered a type of Dynamic Link Library (DLL) file. Dynamic Link Library files, like Startup.cpl, are essentially a "guide book" that stores information and instructions for executable (EXE) files - like MpSigStub.exe - to follow. These files were created so that multiple programs (eg. Startup Control Panel) could share the same Startup.cpl file, saving valuable memory allocation, therefore making your computer run more efficiently.
Unfortunately, what makes DLL files so convenient and efficient, also makes them extremely vulnerable to problems. If something happens to a shared CPL file, either it goes missing or gets corrupted in some way, it can generate a "runtime" error message. Runtime is pretty self-explanatory; it means that these errors are triggered when Startup.cpl is attempted to be loaded either when Startup Control Panel is starting up, or in some cases already running. Some of the most common Startup.cpl errors include:
- Access Violation at address - Startup.cpl.
- Startup.cpl could not be found.
- Cannot find C:\Windows\SysWOW64\Startup.cpl.
- Cannot register Startup.cpl.
- Cannot start Startup Control Panel. A required component is missing: Startup.cpl. Please install Startup Control Panel again.
- Failed to load Startup.cpl.
- The application has failed to start because Startup.cpl was not found.
- The file Startup.cpl is missing or corrupt.
- This application failed to start because Startup.cpl was not found. Re-installing the application may fix this problem.
Your Startup.cpl file could be missing due to accidental deletion, uninstalled as a shared file of another program (shared with Startup Control Panel), or deleted by a malware infection. Furthermore, Startup.cpl file corruption could be caused from a power outage when loading Startup Control Panel, system crash while loading Startup.cpl, bad sectors on your storage media (usually your primary hard drive), or quite commonly, a malware infection. Thus, it's critical to make sure your anti-virus is kept up-to-date and scanning regularly.