OS X Lion and Xcode 4

I have a 2010 Mac Book Pro. I just upgraded to OS X Lion and Xcode 4.1 a few days ago (August 18 to be exact). I gave OS X Lion a 5 star review in App store because I really liked all the new features. I have been using OS X Lion without any problem until I started writing program again using Xcode 4.1. When I try to open a project and I double click a folder, Xcode goes to workspace and the spinning cursor appears as if it is reading something. After a while, the spinning stops and nothing opens. I try to open a project again but this time I just click instead of double click unti I got to the file/project that I wanted to open. The project/file open and everything was fine. Then I tried to duplicate the problem just to make sure. It did it all the time.

And then I wondered if this is only happenning on Xcode. So I tried opening a PDF file on Preview. It did the same thing. When I doubled click a folder, it read all the files in that folder and it locked up. But unlike Xcode that did nothing but a spinning cursor, Preview opened lots of files and there's a counter counting the number of documents and pages that is being opened. Theres thousands of documents and tens and thousands of pages being read. I don't even have that much PDF files in my hard drive. I think it's reading all kinds of files. I was able to stop the Preview by opening Finder, shutdown from there to force quit the Preview. We don't have to be that careful on wether to single click of double click. Do we?

When I double click the first folder there are only subfolders there too. One or two more subfolders before I get to the PDF file that I want to open. Maybe I'm a newbie but isn't it supposed to stay in that folder wether you double click or not until it finds at least one associated file? Does anyone have the same problem or am I losing my mind?