Disclaimer: I'm new here so forgive me if I do something wrong. I recently downloaded Mavericks about a month ago and the setup assistant for Mavericks was trying to make me create a new apple ID. Because of this, I force quit the setup assistant and went on with my life. However, I think this may have some negative effects on the way my computer works now because the Messages app does not even show signs of opening. Im actually not even sure what the app looks like. I have however, been getting occasional iMessage notifications in the upper right corner of my screen. As far as I can tell, I can not respond to these messages and I can only view them in the notification box. Here's the error message I've been getting. http://imgur.com/2LXQwbi If I click "show details" I get a lot of code stuff or something that I do not know how to read. I copied and pasted some of the header that I was able to slightly comprehend (notably the "You don't have permission" section towards the bottom). Here are some of the details of the error message: Process: Messages  Path: /Applications/Messages.app/Contents/MacOS/Messages Identifier: com.apple.iChat Version: 8.0 (4226) Build Info: iChat-4226000000000000~3 Code Type: X86-64 (Native) Parent Process: launchd  Responsible: Messages  User ID: 501 Date/Time: 2014-02-25 21:06:41.494 -0500 OS Version: Mac OS X 10.9.2 (13C64) Report Version: 11 Anonymous UUID: 524CD16F-46B2-D564-943A-32ED3B748FCD Crashed Thread: 0 Dispatch queue: com.apple.main-thread Exception Type: EXC_BAD_INSTRUCTION (SIGILL) Exception Codes: 0x0000000000000001, 0x0000000000000000 Application Specific Information: Sandbox creation failed: You dont have permission to save the file Application Support in the folder Library. Application Specific Signatures: You don?t have permission to save the file ?Application Support? in the folder ?Library?. Again, I've never posted here so if my formatting is off I apologize. Just please try to help me out to get the Messages app working. Thanks in advance!