More puzzlement (perhaps because when we play in the registery, we're beyond my depth), how come:

C:>ftype perl
perl="C:\Perl\bin\perl.exe" "%1" %*
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while regedit doesn't know that? Searching the registery, I find NOTHING for the exact string you posted (meaning, I assume, that I should perhaps set that?) but do find, searching for .pl:

HKEY_CLASSES_ROOT
|  |
|  |
|   .pl  (Default)      REG_SZ   ntpfile
|     |  Content Type   REG_SZ   NoteTab Pro document
|     |  Perceived Type REG_SZ   text
|     |
|      Perl  (Default)      REG_SZ   ntpfile
|         |
|         |
|          ShellNew (Default)      REG_SZ   (value not set)
|
|
 PersistentHandler  (Default)   REG_SZ  {5e941....}
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... the last of which says, "ww go out and RTFM (some more)!"

Thank you.