Booted fine the day before, turned it on today and it got as far as the black screen with the moving Windows logo and just sat there. For hours.
It’d boot into safe mode with no problems.
Eventually I found this forum post which suggested to try booting into safe mode and then uninstalling either the graphics driver or the antivirus software. I tried the graphics driver and it made no difference.
Then I uninstalled the antivirus, which was AVG 2012, and that resolved the problem. PC is booting fine now. So I’ve installed the free Microsoft Security Essentials instead, which I use on all my other PCs anyway. Phew.
Edit: Just found this interesting article where AVG themselves tell you how to disable and then uninstall their product if it stops your PC from booting! Nice. A quick Google search shows that AVG causing this problem is not exactly uncommon…
Robin CM's IT Blog 
We’ve been seeing this issue with AVG – it’s some kind of issue with an update they’ve issued and we’ve got a case open as AVG partners – it has been affecting some (but not all) of our customers with AVG.
We blogged briefly about it here:
http://www.vpwsys.net/blog/june-2015-issue-with-avg-on-some-systems/
We’ve had similar issues with other AV mind you in the past – but this issue affecting Windows 7 machines with AVG is the worst.
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Thanks for the info. This one had me scratching my head for a while, I’ve used various antivirus products on quite a large scale (thousands of PCs and servers) and never seen one cause this.
In this particular installation I had three PCs all running Windows 7 and all running the same version of AVG, yet only one went pop.
If you do hear anything back from AVG I’d be interested to know what they say.
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Have a look at this link.
https://support.avg.com/SupportArticleView?q=Trusteer+&urlname=Computer-does-not-boot-after-Trusteer-Rapport-update&l=en_US
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Interesting – the PC I had problems with does have that installed.
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