Hi Horace,
You can have Perl running with FastCGI Extension for IIS. However since Perl.exe is not a FastCGI now, we recommend running Perl in the default way.
Here are the two threads have latest information on running Perl with FastCGI Extension for IIS:
http://forums.iis.net/p/1137526/1858041.aspx
http://forums.iis.net/t/1107796.aspx
You can check if one issue listed in these threads is the same one as yours. Hope it helps.
Zhao Ji Ma
Sincerely,
Microsoft Online Community Support
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