how can i open proe 5.0 model in pro e 4.0

You can convert file to IGES or STEP format. But you can not modify it.

That's the only way ;-)

hi.. friends please help me Now I have pro-e files How I can convert creo files

You can't open Higher version files in an older version :)

you can not open files from higher version to lower version but you can open lower version file in higher version .if you covert into iges/step format you can open in any version but you can not modify it.......................

instal new version , thats it.....

Wich is the problem? Tell us wich message appear when you try to open the file.