If you're just swapping source code between two different projects; you should be fine w/ copy.
If you're trying to copy the whole project I would do an import / export.
OK...so here's what i did to kind of clean things up and get around the parse error...i have the 2 machine in front of me right now.
On problem machine (machine 1). I deleted the project entirely.
On machine 2 i did an project export ... which created a zip file.
When to machine 1 and did a project inport, pointed to the zip file, openned the project and ...yes, now i can see the design mode and everything looks fine, except...
now i complains that it cannot open c:\<path>\<projectname>\libs
this is kind of confusing as the original project (on machine 2) didn't have a libs directory here...nor am i sure where in the eclipse env't this gets specified.
Libs is a directory created automatically in Flex Builder 3. If you add a SWC in that folder it is automatically added to the classpath.
It was not created in Flex Builder 2.
Could you be having a versioning problem between machines?
Check the classpath / library path in project properties. It may be looking for a hard-coded swc that exists on one machine, but not the other.
Same version of Flex. Actually I think the problem got introduced in the way that i backed up the project. I did it via the export menu but whatever method i used caused empty folders not to get created in the zip file. So the library folder was just missing as it was empty. So on my second attempt i exported it as a project and this time the empty folder was in the archive file. So all is fine.
Thanks so much.