Windows 7: Win7 64bit OEM. Windows services keep crashing. Activation reverting.

Hey everyone. I usually take a certain amount of pride in being able to fix these things myself. But after 12 hours yesterday I'm about ready to flip. Here's my problem...
First, so we're on the same page, system specs:

Intel i5 2500K
Gigabyte Z68X-UD3P-B3
G.Skill Sniper 1600mhz 2x4GB
Inno3D GTX 580
1x OCZ Vertex 3 120GB SSD
2x 500GB HDD
650w Seasonic PSU

Windows 7 Professional 64bit OEM

Everything up to date, all drivers installed. No overclock, no fiddling with RAM timings. No signs of hardware instability.

Now, the story...
Everything was peachy, system works great. Was gettin' my BF3 on. Deus Ex:HR was lots of fun. Then down the right hand near the clock, on the desktop, I got 'Windows 7, build 7601, your copy of Windows is not genuine'.
Basically, I'm having trouble activating Windows. I'll run you through what I've tried...



Tried opening Activation Wizard using 'slui.exe' and 'slui.exe 4' - One of several things happens.
1. Doesn't work, it crashes and gives an error code (next time I can recreate the error I'll include the code.
2. Works, online activation goes smoothly but then 30secs later it goes back to being not genuine. This is sometimes accompanied by error messages saying that the Microsoft Software Protection Platform service has stopped working.
3. Get to phone activation, try and do phone activation except the code I'm given over the phone doesn't work, confirmed multiple times on different occasions. Spoke to a MS rep who couldn't help, transferred me to tech support and they did something on their end, somehow forced an activation. But again, went back to be unactivated.

I've verified Windows files integrity and ran chkdsk numerous times.

Aside from the MS Software Protection Platform also Windows Malicious Software Removal Tool keeps crashing, as does Windows Media Player Sharing service. It happens intermittently. Hasn't happened for about 10mins now, sometimes I'll get consistent, every 30-60secs notifications for about 5mins.

I've tried disabling and reenabling the MS Software Protection via cmd and resetting the licensing info, again to no avail.

These errors happen regardless of what state Windows is in, a clean install right through to updated beyond SP1, also happens with/without antivirus running, other programs etc.

Needless to say, I've reinstalled Windows about 4 times now. At the moment, I've gotten it to a state where Windows is now usable, so I'm reinstalling all my drivers, programs etc.
What I really need, is for Windows to be activated and for these services to stop crashing. I've ruled out a bad install. What on earth could it be?

Parallel to this issue, I had issues reinstalling the most recent time. I had all three drives connected, when I tried to install on the SSD it said "Windows cannot create a partition or locate an existing partition on this drive". What I ended up doing was disconnecting the two HDD's as per tech support guy at MS's request. That worked and I was then able to install Windows again. So now I'm back to having a system I can use...sort of.

I'm aware that I'm using an OEM version of Windows, and that they're locked to the mobo they're first installed with, but surely that wouldn't give you errors and system instability. It would just tell you it can't activate. Right?
Also, other people have reported success just using their OEM version on another machine no probs. My friend has installed it on various systems, always one at a time, without any trouble, legitimately. Also I've heard of talking to Microsoft and saying something like "My mobo got fried and I had to replace it. Can you please pair my product key with my new system." However I tried that and they just shut me down. Now, I'm aware that using an OEM copy on another system isn't totally legit, but I'm really reluctant to fork out upwards of $300 for a new copy of Windows when I have (what was) a fully functioning one already. Especially seeing as I'm unsure if that will fix the problem.

In short, I need to either fix the probem - activate Windows and stop these services crashing, or need to know that the only fix is paying for a new copy of Windows.

I feel bad asking for help because everyone's already been of so much assistance. But after working on this for 12 hours by myself, speaking with 5 different people from Microsoft (product activations right through to 2nd level tech support) and trawling through forums looking for answers I've had enough. Please gimme a hand!

Just now, while writing this post Windows Update won't work, keeps giving error code 0xC002001B. Wait...no now it does work. I ran slui a few times, first two times it gave an error, third time it gave me the option to activate online, which I didn't do, just left it, and now Windows Update works. Seems there's three states it can be in, activated, unactivated and the middle ground where nothing works.

Ok, now just went into System Properties, Windows is now activated. Despite me not touching anything. What the frack. Oh and FWIW I also ran Avira and all disks were clean.

Ok, now Windows Defender just crashed as well. Surely the fact it's OEM wouldn't cause this kind of instability?

To properly analyse and solve problems with Activation and Validation, we need to see a full copy of the report produced by the MGADiag tool (download and save to desktop - http://go.microsoft.com/fwlink/?linkid=52012 )
Once saved, run the tool.
Click on the Continue button, which will produce the report.
To copy the report to your response, click on the Copy button in the tool (ignore any error messages at this point), and then paste (using either r-click/Paste, or Ctrl+V ) into your response.
- **in your own thread**, please
Please also state the Version and Edition of Windows quoted on your COA sticker (if you have one) on the case of your machine, but do NOT quote the Key on the sticker!
http://www.microsoft.com/howtotell/content.aspx?pg=coa

Having said that, I would suspect that there is a hardware problem that is causing all your errors - check the RAM using MemTest86+ for a few hours, and check the hard drive using the drive manufacturer's test utility.