The Microsoft Office Isolated Conversion Environment (Moice) plug-in screens Office 2003 documents for security irregularities, and converts them to Microsoft's new Open XML document format.
Moice opens new documents in a restricted environment, commonly referred to as a sandbox, that prevents an infected file from attacking the operating system, applications and data.
Once the document has been scanned, scrubbed of any potential security irregularities and converted to Open XML, it opens as normal in Office 2003.
Microsoft planned to release Moice on 8 May as part of its monthly Patch Tuesday security release cycle. However, the company said that delays in the non-English versions would affect the global release.
A new release date has not been given, but a company spokesperson indicated that it would be "a matter of weeks".