I came across the COM error:
Invalid parameter error. HRESULT 0x80030057 (STG_E_INVALIDPARAMETER)
when dealing with an Excel interop component called Aspose and couldn't figure out why this error when opening an Excel file. Nor could I find anything here on Stack Overflow so it MUST be asked:
What is the most common cause of this error (in any printed representation) from some black-box COM component?
I will also post what caused my error when SO allows me to!