Mmm, now that's a vague error report if I even saw one!  

What system do you use? What example is troublesome? What kind of error do you have? What do you mean by "exact copy"?

That sounds vaguely like a thing I ran into a while back:

A sketch isn't allowed to have a class with the same name as the name of the sketch.

Internally, Processing converts your sketch into a Java class with the same name as the sketch, so if you also have a class in your pde file with the same name, then there's a problem.

You can run into this unexpectedly in the following way.  Say, for example, you want to write a simulation of hitting a baseball.  You start Processing, and it gives you one of those "sketch_apr08a" kind of filenames.  You begin coding, and decide to encapsulate the properties of a baseball object into a class.  So you create:

class Baseball
{
...
}

Things are working fine.  Your code compiles and runs.  You decide to call it quits for the day, so you do a file->Save As, and choose the name "Baseball.pde".  Processing lets you do this with no trouble.

Next day, you load up Baseball.pde, and find that it won't run.  Now that your sketch has a different name, you have a name collision with the Baseball class you defined.  Goofy, but that's what happens.  Unfortunately, Processing's parser does not detect this situation and warn you about it in any meaningful way, so unless you know you'll be scratching your head for a long time over why your code that worked yesterday suddenly doesn't work today.

Hay thanks for the replies, for some reason I wasn't getting the notification that some one replied to my post.

I can't reproduce it all the time and once it runs without errors, it runs fine after that.

I have "copy + Paste" some of the included examples, run it and I get a bunch of red errors, Java this and Java that. If I run it again, it runs fine after that, with no changes on my part. This has also happened on some small ones I write my self, just playing trying to learn the syntax. I figure this is probably something I am doing wrong, but seems odd that it happens when I copy an example, either from the included example sketch's or copy+paste from the Language web site.

I am running Windows Vista.