I have verified this several times. After I run Comodo Registry Cleaner, Microsoft Office 2003 update fails. The problem and solution is described in the Microsoft Knowledgebase article below.
Title of the article is: “You cannot install an Office 2003 service pack”
The registry cleaner deletes one small entry in the registry and putting it back in fixes the problem. Every time. The article even states that this problem is caused by “aggressive registry cleaners”.