Many of the problems with Word 2007’s stability are due to third-party add-ins that are often used to add functionality to Word and to add new tabs and groups to the ribbon. If something unexpected happens in Word (it crashes, for example) while an add-in is being used, Word will flag it as problematic and will alert you to this the next time Word is launched. Depending on the severity of the problem, the add-in can be either ‘soft-disabled’ or ‘hard-disabled’. More on this a bit later.

In this post, I’ll explain how to programmatically restore add-ins after Word has disabled them. Determining what caused the problem in the first place is outside the scope of this post. However, I’ve watched Word fail to properly start up and blame this on an add-in that has worked without issue for weeks on end. What’s more, after re-loading the add-in, Word and the add-in will work fine for weeks more. So, it may not be a particular add-in is malfunctioning, but that Word’s handling of add-ins generally is flaky.

Microsoft explains the differences between Hard Disabled vs Soft Disabled in a MSDN article at: http://msdn.microsoft.com/en-us/library/ms268871(VS.80).aspx, but I’ll paraphrase here.

Hard-Disabled Add-ins

Hard-disabling occurs when the add-in causes the application (Word) to close unexpectedly. The problem was so serious that Word crashed.

Once an add-in has been ‘hard-disabled’ by Word 2007, it will appear in the Disabled Application Add-ins list. To see which add-ins have been hard-disabled, click on the Office Button | Word Options | Add-Ins, and scroll down to “Disabled Application Add-ins”.

To manually restore a hard-disabled add-in, first enable the add-in by selecting “Disabled Items” in the Manage menu, clicking Go, selecting the add-in to re-enable, and clicking the Enable button. Then load it by selecting “COM Add-Ins” in the Manage menu, clicking Go, and placing a check in the box next to the Add-In.

Each hard-disable add-in will have an entry in the DisabledItems registry key at:

HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Word\Resiliency\DisabledItems

The entry name is some sort of hash/random binary value, rather than the name of the add-in. You can look at the hex of each and identify the specific add-in, but programatically re-enabling them is most easily done by deleting the entire Resiliency key. This makes it an ‘all or nothing’ situation.

Disabling adds a binary value for each addin with a name that’s randomly generated. The Resiliency key exists if there is at least one disabled item, but if you re-enable the addin then the Resiliency key and DisabledItems subkey are both deleted. So the presence of the Resiliency key serves as a general test for the existence of disabled items. You can re-enable the addin by deleting the specific binary reg value, or by removing the whole key.
http://help.lockergnome.com/office/Outlook-constantly-disabled–ftopict876175.html

Soft-Disabled Add-ins

Soft-disabling occurs when an add-in throws an unhandled exception, but the application (Word) does not unexpectedly close.

If an add-in has been ‘soft-disabled’ by Word 2007, it will NOT appear in the Disabled Application Add-ins list. It can be enabled by selecting “COM Add-Ins” in the Manage menu, clicking Go, and placing a check in the box next to the Add-In.

When you re-enable a soft-disabled add-in, Word immediately attempts to load the add-in. If the problem that initially caused Word to soft-disable the add-in has not been fixed, it will soft-disable the add-in again, and the box will not stay checked.

When an add-in has been soft-disabled, the LoadBehavior value in the registry will be changed. It seems that this value can exist in either of two locations:

HKEY_CURRENT_USER\Software\Microsoft\Office\Word\Addins\
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Word\Addins\

A LoadBehavior of 2 = unloaded (this corresponds to an unchecked box)
A LoadBehavior of 3 = loaded (this corresponds to a checked box)

Here’s more information from Microsoft on the various LoadBehavior registry entries.

Restoring disabled add-ins programmatically

Hard-disabled add-ins can be promoted to a temporarily soft-disabled status by running the following registry merge file to delete the Resiliency key:

Windows Registry Editor Version 5.00

[-HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Word\Resiliency]

As an example, Word can be configured to attempt to load the Acrobat PDFMaker Office COM Addin installed with Acrobat 8 Standard by running the following registry merge file to force the data on the LoadBehavior value:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Word\Addins\PDFMaker.OfficeAddin]
"LoadBehavior"=dword:00000003

By enabling the add-ins you wish to always load through the Word GUI, then exporting the Word\Addins registry keys to capture the correct LoadBehavior, and combining those keys with the instruction to delete the Resiliency key, you’ll be able to fix all of your add-in problems and restore Word to a working state with a single click.

A macro to display a message box with all currently loaded COM add-ins

You can use the following macro to display a message box with all currently loaded COM add-ins.

Sub ShowAddins()
'
' ShowAddins Macro
' Display a message box with all currently loaded COM add-ins
'
   Dim MyAddin As COMAddIn
   Dim i As Integer, msg As String

   For Each MyAddin In Application.COMAddIns
      msg = msg & MyAddin.Description & " - " & MyAddin.ProgID & vbCrLf
   Next

   MsgBox msg

End Sub

Source: Some COM add-ins are not listed in the COM Add-Ins dialog box in Word

Forcing add-ins to be disabled by Word

To test, you may be able to cause add-ins to be disabled by forcibly ending the winword.exe process while Word is loading, or after it has invoked a function from the add-in. It might require crashing Word a few times, but eventually you’ll get an error:

Microsoft Office Word
Word experienced a serious problem with the ‘[add-in name]’ add-in. If you have seen this message multiple times, you should disable this add-in and check to see if an update is available.
Do you want to disable this add-in?
[Yes] [No]

If you click Yes, the add-in will be hard-disabled and an entry will be created in

HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Word\Resiliency\DisabledItems