There are several versions depending on your OS. If you want the one for windows..this is what i've found:
PRODUCT: Adobe
Acrobat Exchange
VERSION: 3.0
PLATFORM: Windows
TITLE
AutoClose Plug-in for Windows (16-bit)
ADOBE FTP LOCATIONS
ftp://ftp.adobe.com/pub/adobe/acrobatexchange/win...ugins/closew16.exe
(45K)
ftp://ftp-pac.adobe.com/pub/adobe/acrobatexchange...ugins/closew16.exe
(45K)
DESCRIPTION
You can have up to nine documents open at the same time in Adobe
Acrobat Exchange 3.0 and later and Adobe Acrobat Reader 3.0 and
later. When you attempt to open a tenth document, Exchange or
Reader automatically closes the least recently opened document.
The AutoClose plug-in for Exchange and Reader enables you to
reduce the maximum number of documents open at a time.
for more info: http://mirror.aarnet.edu.au/pub/acrobatreader/win...ugins/closew16.txt
This however is not a plugin for plus! So its posted in the wrong forum...if this isnt what you ment please specify a bit more (wich OS you're using and maybe give the url to where you tried to download it).
---------------------------------------------------------------------------------
Edit: after reading another thread i now know what you are talking about (
http://www.msgplus.net/pluginsdb/down/?action=file&id=108 ) i havent found another site from wich you can download that..i'm sorry.
/ 
