Mac keeps freezing and crashing

Question

Hi,
I'm on a late 2009 iMac (3.06 Intel Core 2 Duo, 12 GB 1067 DDR3, 1TB HD) with Yosemite. I installed Yosemite a few days ago. Previously I ran Mountain Lion.
While on Mountain Lion the mac suddenly started freezing and crashing. I could still move the cursor, and most of the time my sound kept working (although the screen had frozen I could keep on calling via Skype - music and videos mostly stopped working after a minute or so), but I had to force turn off the mac. Upon rebooting most of the time I couldn't get past the start-up screen with the grey progress bar and Apple logo. The problem persists with Yosemite. There isn't any specific program which seems to cause it - I've had crashes running many different things. It doesn't seem to be a kernel panic: I've had only one instance where the grey letters would show up. Otherwise it just crashes.
I've tried many things to fix it already:
- running DiskWarrior and removing corrupted files
- removing dubious third party extensions
- removing unnecessary login items/Launch Daemons/Launch Agents (after running EtreCheck)
- I ran AHT twice (nothing came up) and Rember once (idem)
- ran recovery mode to verify the disk (nothing came up)
- ran Safe Boot for a while (no crashes), which causes me to believe it's a software-related problem.
I reinstalled Yosemite yesterday. It will only boot into safe mode since. While booting normally I can't get past the white screen.
About three months ago a faulty HD was replaced and RAM (8 GB) was added, both done in an Apple store. I've no reason yet to believe it's hardware-related because every test comes up clean, but I'm obviously not sure.
I don't know what to do next other than bringing it to the store. Any help would be much appreciated. Because I'm in safe mode my EtreCheck report differs from the normal report - if it's helpful to post it anyway, I will.
Thanks!

Answer 1

EtreCheck version: 2.1.6 (109)
Report generated 29 janvier 2015 10:43:44 UTC+1
Télécharger EtreCheck à http://etresoft.com/etrecheck
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Informations matérielles : ℹ️
  iMac (27-inch, Late 2009) (Caractéristiques techniques)
  iMac - modèle : iMac11,1
  1 2.8 GHz Intel Core i7 CPU : 4-core
  16 GB RAM Extensible
  BANK 0/DIMM0
  4 GB DDR3 1067 MHz ok
  BANK 1/DIMM0
  4 GB DDR3 1067 MHz ok
  BANK 0/DIMM1
  4 GB DDR3 1067 MHz ok
  BANK 1/DIMM1
  4 GB DDR3 1067 MHz ok
  Bluetooth: Vieux - Handoff/Airdrop2 pas disponible
  Wireless:  en1: 802.11 a/b/g/n
Informations vidéo : ℹ️
  ATI Radeon HD 4850 - VRAM : 512 MB
  iMac 2560 x 1440
Logiciel du système : ℹ️
  OS X 10.9.5 (13F34) - Temps depuis le démarrage : 18:31:17
Informations des disques : ℹ️
  WDC WD10EARS-00Y5B1 disk0 : (1 TB)
  EFI (disk0s1) <non monté>  : 210 Mo
  Macintosh HD (disk0s2) /  : 999.35 Go (976.07 Go libre)
  Recovery HD (disk0s3) <non monté>  [Restauration] : 650 Mo
  HL-DT-ST DVDRW  GA11N 
Informations USB : ℹ️
  composite_device 7,81 GB
  EFI (disk2s1) <non monté>  : 210 Mo
  OS X Mavericks Installer (disk2s2) /Volumes/OS X Mavericks Installer  : 7.47 Go (1.40 Go libre)
  Toshiba External USB 3.0 1 TB
  EFI (disk4s1) <non monté>  : 210 Mo
  Back up Imac (disk4s2) /Volumes/Back up Imac  : 999.86 Go (293.01 Go libre)
  Apple Inc. BRCM2046 Hub
  Apple Inc. Bluetooth USB Host Controller
  Apple Internal Memory Card Reader
  Western Digital My Passport 070C 499,41 GB
  EFI (disk1s1) <non monté>  : 210 Mo
  WD boot (disk1s2) /Volumes/WD boot  : 498.55 Go (472.71 Go libre)
  Recovery HD (disk1s3) <non monté>  [Restauration] : 650 Mo
  Logitech Optical USB Mouse
  Apple Inc. Built-in iSight
  Apple Computer, Inc. IR Receiver
Gatekeeper : ℹ️
  Mac App Store et développeurs identifiés
Extensions du noyau : ℹ️
  /Library/Extensions
  [engagé] at.obdev.nke.LittleSnitch (4228 - SDK 10.8) [Aide]
Agents de lancement : ℹ️
  [en marche] at.obdev.LittleSnitchUIAgent.plist [Aide]
  [désengagé] com.adobe.AAM.Updater-1.0.plist [Aide]
Daemons de lancements : ℹ️
  [en marche] at.obdev.littlesnitchd.plist [Aide]
  [engagé] com.adobe.fpsaud.plist [Aide]
  [invalid?] com.lsreset.plist [Aide]
Éléments Ouverture : ℹ️
  Aucun
Plug-ins internets : ℹ️
  FlashPlayer-10.6 : Version : 16.0.0.296 - SDK 10.6 [Aide]
  Flash Player : Version : 16.0.0.296 - SDK 10.6 [Aide]
  QuickTime Plugin : Version : 7.7.3
  JavaAppletPlugin : Version : 14.9.0 - SDK 10.7 Vérifier la version
  Default Browser : Version : 537 - SDK 10.9
Plug-ins internets pour l’utilisateur : ℹ️
  Dashlane : Version : Dashlane 1.0.0 - SDK 10.10 [Aide]
Extensions de Safari : ℹ️
  Dashlane [Installé]
Panneaux de préférences tiers : ℹ️
  Flash Player  [Aide]
Time Machine : ℹ️
  Time Machine n’est pas configuré !
L’utilisation du CPU par processus : ℹ️
      3% WindowServer
      1% fontd
      1% Safari
      0% PluginProcess
      0% Dashlane
L’utilisation de la RAM par processus : ℹ️
  515 Mo WebKitPluginHost
  395 Mo com.apple.WebKit.WebContent
  378 Mo firefox
  326 Mo Safari
  223 Mo PluginProcess
Informations de la mémoire virtuelle : ℹ️
  7.06 Go RAM Disponible
  7.25 Go RAM Active
  1.50 Go RAM Inactive
  1.35 Go RAM Résidente
  1.80 Go Pages entrants
  0 o Sorties pages
Informations du diagnostic : ℹ️
  Jan 28, 2015, 10:45:51 PM /Users/[expurgé]/Library/Logs/DiagnosticReports/PokerStarsFR_2015-01-28-224551_ [expurgé].crash
  Jan 28, 2015, 04:13:07 PM Examen de soi - succès