We have a number of clients who are using the latest and – in my opinion – greatest version of Windows – Windows 7. Also, with the price of memory dropping to new lows, users are opting for a 64-bit version of Windows 7 (to address the 4GB RAM limitations of a 32-bit memory address).
Issue
On these 64-bit Windows 7 machines, users began reporting a generic CRM error message while starting Mail Merge functionality in CRM. The concern was, not every user was experiencing this issue, and all users were on the same rollup level and OS/application level (at first, it was not clear to us that differences in memory address was an issue).

We enlisted the help of Microsoft Support, and with the gold standard service that several senior support engineers provide (Dan) were able to determine that the cause of the issue is not caused by a bug within CRM, but rather an issue with Windows 7 x64.
Specifically, when CRM calls to open an Internet Explorer window, it incorrectly reads a registry value, causing a 64-bit IE window to open instead. Since the CRM client code is written as a 32-bit app, a 32-bit operation cannot be made in a 64-bit IE window causing the Mail Merge to fail.
Solution
The solution below (provided by Microsoft Support) applies only to 64-bit versions of Windows 7. The solution does not apply for 32-bit versions of Windows 7 (there should be no issues). If you are finding Mail Merge issues in a 32-bit Windows 7 environment, consider reviewing the latest Rollup for more details.
You will need the following:
1 a) Extract IE64bitFix.ps1 from the IE64BitFix.zip file.
b) Change ownership of the script to be a local admin user for the machine.
c) Login as the local admin for that machine.
2. Launch Regedit (right click and Choose ‘Run As Administrator’)
3. Navigate to HKLM:\SOFTWARE\Wow6432Node\Classes\CLSID\{D5E8041D-920F-45e9-B8FB-B1DEB82C6E5E}
4. Right-click on the key and choose Permissions.
5. If the TrustedInstaller user appears in the list, remove it. Make sure the Administrator user has Full Control on the key and its subkeys.
6. If you run into an error removing the TrustedInstaller, click on Advanced and then on the owner tab, change the owner.
7. Close the Registry Editor.
8. Launch Powershell doing the following:
a. Start > All Programs > Accessories > Windows Powershell.
b. Right click on Windows Powershell ISE
c. Choose ‘Run As Administrator’
d. Copy the attached Powershell script to the machine.
e. Choose File > Open in the Powershell UI and select the powershell script you copied to the machine.
f. Press F5 or the Green Go button to execute the script
9. Start Outlook and verify the fix.
Some users have reported a need to apply less security restrictions by running the Set-ExecutionPolicy cmdlet prior to executing the script. To do this in Powershell:
1. Apply no restrictions, so that all Windows Powershell scripts can be run
Set-ExecutionPolicy Unrestricted
2. Apply the Powershell script as detailed in step 8
3. Return to allowing only signed scripts (or Restricted, or RemoteSigned)
Set-ExecutionPolicy AllSigned
Update – Exporting to Excel from a SharePoint iFrame
As a double bonus on this issue, clients have reported that using these steps, they are now able to open Excel documents within Excel, from a SharePoint iFrame in the CRM. Prior to the fix, Excel document would open within the confinements of the iFrame window in a CRM record.