This bug was originally marked as duplicate of bug 153664, that is already resolved. This bug is still valid, so this seems to be another bug, but it might be related.
Build: NetBeans IDE 7.4 RC1 (Build 201309162201)
VM: Java HotSpot(TM) 64-Bit Server VM, 25.0-b50, Java(TM) SE Runtime Environment, 1.8.0-ea-b108
OS: Windows 7
faramir2: I don't know how can I reproduce this one, but I copied one .java file WaitTests.java (with public static void main(String args) method) to new file LockTets.java (both files were in waittests source package). Then I changed Object to Lock and assigned ReentrantLock. Then I pressed CTRL+SHIFT+I and then I had problem - it was unable to click OK or Cancel; moreover, window shows unknown class 'i' but I had 'i' only as variable name and 'int' was before. I was able to close that window by pressing ESC key. After some time, after pressing CTRL+SHIFT+I again, I was able to fix import, but I had problem with code completion and code assistant (empty, not showing...)
Created attachment 140624 [details]
This bug already has 5 duplicates
Created attachment 165548 [details]
I copied a class (with refactor) to a new class.
After that Netbeans stopped to compile anything