Description:
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Using IIS, the php5isapi.dll module fails to load certain extensions even though the file is in the location indicated by the error message.  The main module of importance to me is php_pdf.dll, though I have also tried libpdf_php.dll and uncommented some of the other extensions with the same result.

Reproduce code:
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No code required.  When the ISAPI module loads and attempts to load the extensions, errors occur.

Expected result:
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No errors.  PDF files produced.

Actual result:
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The ISAPI module displays an error message indicating that E:\PHP\ext\php_pdf.dll (or other module) can't be found, even though the file is in that location.  IIS hangs until the dialog box is cleared.  The PHP ISAPI module appears to operate after that, except for the functions that require the extensions that did not load.