Summary of issue: There is no way to mail merge to labels for more than a two accounts without Outlook crashing in 5 completely different environments when the following recreate steps are followed precisely.

I can make this merge work on any 1 account, but it won't work when I choose more than two. If you attempt to recreate these circumstances, please try selecting more than 10 accounts to ensure the error occurs. I was able to replicate this error on my personal CRM instance, three of my client's machines, and Eric Hula replicated this behavior by following my steps when he heard about it on twitter.

I have some more detailed notes in this forum thread for this issue:
http://social.microsoft.com/Forums/en-US/crm/thread/fd4eed2c-0dd3-407e-8735-705b9c2a23c1

Finalized Recreate steps:

1. Start Outlook that is configured against a CRM 4.0 On-Premise instance over IFD (HTTPS).

2. Select a few accounts in outlook.

3. Click the Mail Merge button.

4. In the "Select the mail merge type:" drop down, select "Label".

5. Click OK.

6. Once word opens, click OK.

7. Once Label Options shows up, choose "Page Printers", Tray: "Default tray (Automatically Select)", Label Venders: "Avery A4/A5", Product Number: "4805". Then Click OK.

8. Click "Next: Arrange your labels" on the bottom right-hand corner of the word screen.

9. Now click OK again on the label options tab that stupidly shows up again! (Maybe this is the problem?)

10. Click OK on the "In order to apply the selected options, Word must delete the current contents of Document1. Any unsaved changes to this document will be lost."

11. Click "Address block..." from the "Arrange your labels" section.

12. Click OK on the Insert Address Block window.

13. Click "Update all labels".

14. Click "Next: Preview your labels" on the bottom right-hand corner of the word screen.

15. Click "Next: Complete the merge" on the bottom right-hand corner of the word screen.

16. Click "Print..." on the right side of the word screen under the "Complete the merge" section.

17. Click Ok on the Merge to Printer window.

18. Click OK on the Print screen after choosing a printer.

ERROR OCCURS

19. Window that gives you the option to create activities for this merge DOES NOT appear.

20. Print succeeds.


Error details:

Event Type: Error

Event Source: C:\Program Files\Microsoft Office\Office12\OUTLOOK.EXE

Event Category: None

Event ID: 5000

Date: 3/22/2010

Time: 1:22:48 PM

User: N/A

Description:

The description for Event ID ( 5000 ) in Source ( C:\Program Files\Microsoft Office\Office12\OUTLOOK.EXE ) cannot be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer. You may be able to use the /AUXSOURCE= flag to retrieve this description; see Help and Support for details. The following information is part of the event: crmunmanaged, 4.0.7333.2138, outlook.exe, 629, c__bt_13487_src_application_outlook_addin_mailmerge.cpp, NIL, NIL, NIL, NIL, NIL, NIL.

Data:

0000: 63 00 72 00 6d 00 75 00 c.r.m.u.

0008: 6e 00 6d 00 61 00 6e 00 n.m.a.n.

0010: 61 00 67 00 65 00 64 00 a.g.e.d.

0018: 2c 00 20 00 34 00 2e 00 ,. .4...

0020: 30 00 2e 00 37 00 33 00 0...7.3.

0028: 33 00 33 00 2e 00 32 00 3.3...2.

0030: 31 00 33 00 38 00 2c 00 1.3.8.,.

0038: 20 00 6f 00 75 00 74 00 .o.u.t.

0040: 6c 00 6f 00 6f 00 6b 00 l.o.o.k.

0048: 2e 00 65 00 78 00 65 00 ..e.x.e.

0050: 2c 00 20 00 36 00 32 00 ,. .6.2.

0058: 39 00 2c 00 20 00 63 00 9.,. .c.

0060: 5f 00 5f 00 62 00 74 00 _._.b.t.

0068: 5f 00 31 00 33 00 34 00 _.1.3.4.

0070: 38 00 37 00 5f 00 73 00 8.7._.s.

0078: 72 00 63 00 5f 00 61 00 r.c._.a.

0080: 70 00 70 00 6c 00 69 00 p.p.l.i.

0088: 63 00 61 00 74 00 69 00 c.a.t.i.

0090