Disk corruption, likely HDD corruption!
Thus you shall get and run Memtest86.
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A RAM problem can cause the following symptoms:
1. Windows falsely says that a file can't be found.
Often appears in the message box variant, with an OK button.
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2. Windows displays the error message saying that MSGINA.DLL failed to initialize.
You also probably can't log in when this error message appears.
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3. Windows always crashes on you when in normal mode, but fine in safe mode!
You have to use safe mode just to use Windows!
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