If you are using Windows XP Pro then use the Group Policy editor. Type:
gpedit.msc
in the Run dialog box or Command Prompt. Then Navigate to:
User Configuration > Administrative Templates > Windows Components >
Internet Explorer
and/or
Computer Configuration > Administrative Templates > Windows Components >
Internet Explorer
Locate and double-click "Do not allow users to enable or disable add-ons".
Change the setting to "Not Configured".
Also check:
User Configuration > Administrative Templates > Windows Components >
Internet Explorer > Security Features > Add-on Management
and/or
Computer Configuration > Administrative Templates > Windows Components >
Internet Explorer > Security Features > Add-on Management
Locate and double-click "Deny not all add-ons unless specifically allowed in
the Add-on List" and "Ad-on List"
Change the setting to "Not Configured".
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If you are using Windows XP Home then you will need to edit the registry.
Navigate to:
[HKLM\SOFTWARE\Policies\Microsoft\Internet Explorer\Restrictions]
and/or
[HKCU\SOFTWARE\Policies\Microsoft\Internet Explorer\Restrictions]
Delete "NoExtensionManagement".
Also Check:
[HKLM\Software\Microsoft\Windows\CurrentVersion\policies\EXT\CLSID]
and
[HKCU\Software\Microsoft\Windows\CurrentVersion\policies\EXT\CLSID]
You will need to know the Adobe CLSID, when you do simply the delete the
CLSID. An CLSID looks like "{17492023-C23A-453E-A040-C7C580BBF700}".
Also Check:
[HKLM\Software\Microsoft\Windows\CurrentVersion\policies\EXT]
and
[HKCU\Software\Microsoft\Windows\CurrentVersion\policies\EXT]
Delete "RestrictToList".
You may need to restart your computer for the changes to apply.
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If you are unsure on how to edit the registry then you can download the
following registration file from my website to your desktop. Right-click
"enable.manage.addons.reg" to select "merge" and merge the file into the
registry. You can view the registration file by right-click the file and
select "edit".
Enable Manage Add-ons Registration File
http://www.lprf.ca/files/enable.manage.addons.reg