“Unspecified error” when replying mail in outlook 2003

Hi there, got this irriating problem with my company’s outlook 2003. When my user tired to reply back a certain email or saving it as Draft, outlook will prompt “Unspecified Error”.

The only way is to uncheck the “Use Microsoft Word to edit emails message”, detect adn repair does not helps either. IS there any other ways to go around this problem?

Thanks!