Document Information Panel was unable to load

Last week I was working on an strange issue. Some of the users were getting "The Document Information Panel was unable to load. The document will continue to open. For more information, contact your system administrator." when ever they try to open the office document from an WSS 3.0 site.

On analysing found one column in the library had flower braces {} in its description. Replacing the {} with () dissappered the error message.