*Clearing the cache usually fixes it.

Navigate to the following Uniform Resource Locator (URL) to download the Electronic Forms Designer Runtime update:

Click Download Now. In the File Download dialog box, click Save This Program to Disk.

 Select a location on your local computer, and then click Save.

How to Install the Electronic Forms Designer Runtime Update

1.Double-click the EFD.exe package file that you downloaded.

2Click Yes when you receive the first prompt, and then click Yes to accept the license agreement.

3. Click OK to acknowledge that the installer has completed.

How to use the Electronic Forms Designer Runtime Update

1.Start Outlook 2002.2.On the Tools menu, click Forms, and then click Choose Form. 3.In the Choose Form dialog box, click Organizational Forms Library in the Look In drop-down box.

4. Select the form that you want, and then click Open to view and begin working in your form.

Source:http://support.microsoft.com/?kbid=288279

IF its not solved your problem then also check

http://www.kbalertz.com/kb_839804.aspx

But if its the below case then its not solved yet

http://www.kbalertz.com/kb_Q253472.aspx

Sorry for the OL 2002 issue that I gave.

As I said http://support.microsoft.com/?kbid=253472 this is not solved. But this can be possible clearing the cache.

How to clear Cache

If you are using Microsoft Outlook 2000 SR-1/SR-1a and you have Outlook 2000 configured in the Corporate/Workgroup (CW) mode, you can use the Clear Cache button to reset the Outlook forms cache.

Else
Use the following steps to use the Clear Cache button:
1. On the Tools menu, click Options, and then click the Other tab.
2. Click Advanced Options.
3. In the Advanced Options box, click Custom Forms.
4. In the Custom Forms box, click Manage Forms.
5. In the Forms Manager box, click Clear Cache.