Absence of this trailing backslash prevents location of the Csapi3t1.dll file and causes the spelling checker not to function correctly.
The Csapi3t1.dll file is missing or damaged. The Csapi3t1.dll file is located in the Program Files\Common Files\Microsoft Shared\Proof folder,
The Mssp232.dll or Mssp2_en.lex file is missing or damaged.
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows
To resolve this issue, use Registry Editor to verify that the value data in the SharedFilesDir registry value contains a trailing backslash:
Click Start, click Run, type Regedt32, and then click OK.
Double-click to expand the HKEY_LOCAL_MACHINE folder, expand the Software folder, and then expand the Microsoft folder.
Double-click to expand the Shared Tools folder, and then click the SharedFilesDir value.
On the Edit menu, click Modify.
Type C:\Program Files\Common Files\Microsoft Shared\ in the Value Data box, and then click OK.
Quit Registry Editor.
The value data for the SharedFilesDir registry value should point to the folder that contains the Proof folder. The Proof folder contains the Csapi3t1.dll file.
In order for the Spelling checker to work, the software needs a dictionary to compare words against. However, Outlook Express is offered as a downloadable product, and it does not include its own dictionary. Outlook Express does can use another programs dictionary, such as Microsoft Word, to check the spelling of text. Without another program's dictionary to access, Outlook Express cannot use the spelling checker.