Messages goes unresponsive a couple of seconds after launching - any fix? I am running OS X 10.9 on a late 2009 iMac with 12 GB of RAM.

Until a couple of weeks ago, Messages ran fine. But as of a couple of weeks ago it goes unresponsive (spinning beach ball) a few seconds after startup. There is enough time to do something quick, like logout of my AIM account, or go into Preferences. But not enough time to actually check different preferences before it beachballs.

I must force quit. The error report for Apple says it is in a hanged state. Below I've included part of the (long) report. From all the indents it looks like something recursive is happening.

I've deleted everything I could think of from Library - all the im and ichat related plist files. The entire Messages folder. Nothing helps. Nobody at the Apple support forums seems to have any ideas.

Of course I've restarted. And deleted the imagent process from active processes too (it immediately reappears).

At this point I don't care if I lost all old messages and account settings. I don't mind setting things up again. I'd like to just get Messages to work again. 

Any ideas?

Date/Time:       2013-12-14 22:33:02 +0900
OS Version:      10.9 (Build 13A603)
Architecture:    x86_64
Report Version:  18

Command:         Messages
Path:            /Applications/Messages.app/Contents/MacOS/Messages
Version:         8.0 (4218)
Build Version:   16
Project Name:    iChat
Source Version:  4218000000000000
Parent:          launchd [246]

PID:             28662
Event:           hang
Duration:        1.02s
Steps:           11 (100ms sampling interval)

Hardware model:  iMac10,1
Active cpus:     2
Fan speed:       999 rpm

Free pages:      304622 pages (+21114)
Pageins:         0 pages
Pageouts:        0 pages
Swapins:         0 pages
Swapouts:        0 pages


Process:         Messages [28662]
Path:            /Applications/Messages.app/Contents/MacOS/Messages
Architecture:    x86_64
Parent:          launchd [246]
UID:             501
Task size:       27616 pages (+498)
CPU Time:        0.743s

  Thread 0xa6ee94   DispatchQueue 1          priority 0          cpu time   0.742s
  10 start + 1 (libdyld.dylib) [0x7fff9643d5fd]
    10 NSApplicationMain + 940 (AppKit) [0x7fff92ecb803]
      10 -[NSApplication run] + 553 (AppKit) [0x7fff92ee09cc]
        10 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 122 (AppKit) [0x7fff92eec8db]
          10 _DPSNextEvent + 1434 (AppKit) [0x7fff92eed28e]
            10 _BlockUntilNextEventMatchingListInModeWithFilter + 65 (HIToolbox) [0x7fff9233cabc]
              10 ReceiveNextEventCommon + 479 (HIToolbox) [0x7fff9233ccb7]
                10 RunCurrentEventLoopInMode + 226 (HIToolbox) [0x7fff9233cf0d]
                  10 CFRunLoopRunSpecific + 340 (CoreFoundation) [0x7fff93acc294]
                    10 __CFRunLoopDoObservers + 391 (CoreFoundation) [0x7fff93adb017]
                      10 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23 (CoreFoundation) [0x7fff93adb0a7]
                        10 CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) + 71 (QuartzCore) [0x7fff90f277a1]
                          10 CA::Transaction::commit() + 388 (QuartzCore) [0x7fff90f17016]
                            10 CA::Context::commit_transaction(CA::Transaction*) + 236 (QuartzCore) [0x7fff90f1737c]
                              6 CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 35 (QuartzCore) [0x7fff90f178f1]
                                6 CA::Layer::display_if_needed(CA::Transaction*) + 590 (QuartzCore) [0x7fff90f181a2]
Well, after a few weeks I finally managed to "fix" it, even though it meant losing my message history on my iMac.

(1) I deleted all the plist and preferences and caches and anything related to messages or chat.

(2) I restarted in Safe mode. I saw that Messages did start up again, as an empty shell, but it started up.

(3) I then restarted in normal mode. 

Messages then started up again. I had to login to my AIM account again, but my buddy list is maintained by them, so that was all there. And I had to reset my iMessage settings. 

But at least it is working again, finally.