Erwin 4 file to Visio? Are there converters?

Hi,

Someone in my company got a file created in Erwin 4. But we only have Erwin 3.5 and so it cannot open that file. We are looking for a way to convert the file to either Erwin 3 or 3.5 or Visio 2000.

Does anybody know if there is a file converter that can convert this file?
It is about 3.5MB and contains confidential information.

Thanks