Well, I don't use avast, but if it's like other anti-virus programs, look if there's a list of blocked programs. If there is, greenfoot might be under there. Just remove it from that list. Also, you may have something else in your normal windows firewall (I've experienced the same thing just randomly on normal windows). If you're on windows 7, or maybe vista, you can search up "firewall" from the start menu. Click on "Windows Firewall" (not with advanced settings) and then go to "Allow a program or feature through Windows Firewall". From there, I believe you need to make sure all "Java(TM) Platform SE Binary"s are allowed (I think) at least on private. Also look for greenfoot, and say the same thing. If it's not working, check both "private" and "public". There may be something similar to Windows Firewall through avast instead for you. Just follow a similar path through avast, if it's similar at all. You will need administrator's permission to change stuff like this. I hope this helps, I'm not 100% sure what the problem is, but it's what I know for now.

I guess you meant Avast! Please see http://www.greenfoot.org/doc/firewall for general information. Basically, if Avast stops Greenfoot from working, then Avast is doing something wrong.

I deactived my firewall and avast but get the same error: Greenfoot run started: Thu Oct 24 17:58:43 CEST 2013 Greenfoot version: 2.3.0 Java version 1.7.0_21 Virtual machine: Java HotSpot(TM) Client VM 23.21-b01 (Oracle Corporation) Running on: Windows 8 6.2 (x86) Java Home: E:\jdk\jre ---- Internal error: Could not launch RMI server Exception message: Connection refused to host: 127.0.0.1; nested exception is: java.net.ConnectException: Connection timed out: connect java.rmi.ConnectException: Connection refused to host: 127.0.0.1; nested exception is: java.net.ConnectException: Connection timed out: connect at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:619) at sun.rmi.transport.tcp.TCPChannel.createConnection(TCPChannel.java:216) at sun.rmi.transport.tcp.TCPChannel.newConnection(TCPChannel.java:202) at sun.rmi.server.UnicastRef.newCall(UnicastRef.java:340) at sun.rmi.registry.RegistryImpl_Stub.rebind(Unknown Source) at java.rmi.Naming.rebind(Naming.java:177) at rmiextension.BlueJRMIServer.<init>(BlueJRMIServer.java:111) at rmiextension.RMIExtension.startup(RMIExtension.java:60) at bluej.extmgr.ExtensionWrapper.safeStartup(ExtensionWrapper.java:533) at bluej.extmgr.ExtensionWrapper.newExtension(ExtensionWrapper.java:209) at bluej.extmgr.ExtensionsManager.loadDirectoryExtensions(ExtensionsManager.java:164) at bluej.extmgr.ExtensionsManager.loadExtensions(ExtensionsManager.java:100) at bluej.extmgr.ExtensionsManager.getInstance(ExtensionsManager.java:61) at bluej.Main.processArgs(Main.java:179) at bluej.Main.access$000(Main.java:55) at bluej.Main$1.run(Main.java:97) at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:727) at java.awt.EventQueue.access$200(EventQueue.java:103) at java.awt.EventQueue$3.run(EventQueue.java:688) at java.awt.EventQueue$3.run(EventQueue.java:686) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) at java.awt.EventQueue.dispatchEvent(EventQueue.java:697) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138) at java.awt.EventDispatchThread.run(EventDispatchThread.java:91) Caused by: java.net.ConnectException: Connection timed out: connect at java.net.DualStackPlainSocketImpl.connect0(Native Method) at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:69) at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339) at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200) at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:157) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:391) at java.net.Socket.connect(Socket.java:579) at java.net.Socket.connect(Socket.java:528) at java.net.Socket.<init>(Socket.java:425) at java.net.Socket.<init>(Socket.java:208) at sun.rmi.transport.proxy.RMIDirectSocketFactory.createSocket(RMIDirectSocketFactory.java:40) at sun.rmi.transport.proxy.RMIMasterSocketFactory.createSocket(RMIMasterSocketFactory.java:146) at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:613) ... 29 more Commencing network test... Local host address = 212.5.13.214 Local host ip = 212.5.13.214 Addresses for 'localhost': -> 127.0.0.1 -> 0:0:0:0:0:0:0:1 (end of list). Creating unbound server socket... Successful. Creating server socket bound to 127.0.0.1... Successful. Attempting to connect to 127.0.0.1:53257 with NO_PROXY... Successful. Attempting to connect to 127.0.0.1:53257... Successful. Creating server socket bound to 0:0:0:0:0:0:0:1... Successful. Attempting to connect to 0:0:0:0:0:0:0:1:53260 with NO_PROXY... Successful. Attempting to connect to 0:0:0:0:0:0:0:1:53260... Successful. Creating server socket bound to 212.5.13.214... Successful. Attempting to connect to 212.5.13.214:53263 with NO_PROXY... Successful. Attempting to connect to 212.5.13.214:53263... Successful. Network test complete.

There is definitely something on your system that is stopping communication between the two Greenfoot processes. I'm afraid I can't tell any more than that from the log :( If it was working before you installed Avast, this suggests that Avast causes the problem.

This problem is caused by Avast latest update, see this: http://stackoverflow.com/questions/19392087/cant-connect-to-localhost-after-avast-antivirus-latest-update I also have Avast security software and I'm relieved that Greenfoot support was able to identify this problem for me. Now, since re-installing Avast didn't work, I'm trying to figure out if there's any way I can keep my Avast software installed and still use Greenfoot. If you find a way, please post.