The last time I opened up my jSuneido project in Eclipse on my Mac at home I had an error. But I hadn't had an error on Windows at work.
It turned out I was using a method (Arrays.copyOfRange) that was introduced in 1.6
The default for the Mac still appears to be Java 1.5
To "fix" this go into Eclipse > Preferences > Java > Installed JREs and pick 1.6
PS. Don't forget to enable asserts in the newly chosen JRE (like I did!)