libexpatw.dll is considered a type of Dynamic Link Library (DLL) file. Dynamic Link Library files, like libexpatw.dll, 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. Trend Micro Antivirus Plus Security) could share the same libexpatw.dll 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 DLL 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 libexpatw.dll is attempted to be loaded either when Trend Micro Antivirus Plus Security is starting up, or in some cases already running. Some of the most common libexpatw.dll errors include:
- Access Violation at address - libexpatw.dll.
- libexpatw.dll could not be found.
- Cannot find C:\Windows\Temp\TrendMicro AntiThreat Toolkit\HC_ATTK\libexpatw.dll.
- Cannot register libexpatw.dll.
- Cannot start Trend Micro Antivirus Plus Security. A required component is missing: libexpatw.dll. Please install Trend Micro Antivirus Plus Security again.
- Failed to load libexpatw.dll.
- The application has failed to start because libexpatw.dll was not found.
- The file libexpatw.dll is missing or corrupt.
- This application failed to start because libexpatw.dll was not found. Re-installing the application may fix this problem.
Your libexpatw.dll file could be missing due to accidental deletion, uninstalled as a shared file of another program (shared with Trend Micro Antivirus Plus Security), or deleted by a malware infection. Furthermore, libexpatw.dll file corruption could be caused from a power outage when loading Trend Micro Antivirus Plus Security, system crash while loading libexpatw.dll, 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.