What you have to do is unmount the filesystem and remount it where the files are at that you want to run. It's telling you that the java file you opened is a valid and working java program but the relying class/java, CountChar.java, isn't in the same directory as the mounted file system. The way NetBeans works is you have a filesystem in which it works. If you mount "C:\Dev" and you have a java app in it. You will need to make sure that "C:\Dev" has the files you want to run in it from the IDE. Example. I have a.java and b.java in "C:\Dev". I open a.java but I have "C:" mounted. Since a.java relies on b.java, NetBeans looks in my mounted filesystem(s) to find the b.java file. Since b.java is in "C:\Dev", a.java compiles because there are no coding errors but b.java isn't in the current filesystem and thus, will cause the error. If by chance, this isn't the case, make sure that the files are in the same directory as you did not include any package in your .java file. Let me know, Jeremy