In response to customer requests, Aladdin has released StuffIt
Expander(tm) 5.1.3, an optional upgrade that allows users to turn off
the Internet file mappings, currently set for .sit and .pf, in
Expander’s preferences. StuffIt Expander 5.1.3 is a FREE, optional
upgrade available for download directly from Aladdin’s update web
page at:

StuffIt Expander versions 5.1, 5.1.1 and 5.1.2 automatically set the
Internet Preferences to map StuffIt archives and Private File(tm)
files to their parent (creator) applications, StuffIt Deluxe(tm) and
Private File, and set the post processor application (how to open the
file after downloading) to StuffIt Expander. Microsoft Internet
Explorer ignores Expander as the designated Post Processor to open
these files and instead chooses the parent applications, if
installed, to open them. If the creator applications are not found,
the files will not be opened by StuffIt Expander automatically, as

This optional upgrade no longer sets a user’s Internet control panel
preferences to automatically expand StuffIt (.sit) or Private File
(.pf) files with the StuffIt Deluxe parent application. This will
allow users of Microsoft Internet Explorer to again automatically
expand files with Expander. Once the preference has been changed,
Expander will not reset the .sit and .pf file mappings automatically,
as it did in previous versions of Expander.

StuffIt Expander 5.1.3 installs a new version of StuffIt Expander,
which can replace Expander version 5.1.2. Users of Expander versions
5.1.1 and earlier should upgrade to Expander 5.1.2 or 5.1.3. For more
information on StuffIt Expander, visit: