Hello all, (Preemptive warning: English is not my native language…) My Macbook pro mid-2010 has been acting out lately, to the point of being nearly unusable. For four days now I’ve been browsing forums and trying various fixes, but I’m now at my wit's end and badly need advice as to what my next move should be. As you can guess, my warranty is long expired. Symptoms: overall slowdown. Slow startup, beach ball of death my constant companion, multitasking a dream of the past. Having to keep my phone close at hand so as to have something to play with while I wait for apps to startup and sometimes to perform a new command (sometimes they almost run fine once they've opened). ((A simple added attraction at this point : since I've reinstalled the OS, every time I try to change my security settings to allow the installation of outside apps, it automatically changes back to default settings.)) All this started about a week ago (my mac’s performance had started to drop before that, but nothing really worth worrying about), and I can’t think of anything I’ve done or installed or changed to cause it. So far, I’ve… Ran OnyX and fixed my hard drive (yep, it needed fixing). No help there. Wiped my hard drive and clean installed Yosemite (I’ve been running Yosemite almost since it came out, without noticing any impact on my mac’s performance). The reinstall didn’t go smoothly : I had to force a reboot as it got stuck on startup. The installation did complete from then on. Tried to run AHT thrice (once the full test, twice the normal one), without success. The test gets stuck near the end and stalls there for hours. Rechecked my drive (with disk utility) and got a clean bill of health. SMART verified. Permissions ok. Reset the NVRAM Reset the SMC Cursed an ungodly number of times. And now, the dilemma: should I embark on a long and most likely costly journey with the good people of Apple Store, or just assume that my good old companion is sadly due to be replaced by the next gen ? Or is there a middle-ground solution that you can think of ? Thank you so much in advance for your advices.