Not getting image and folder previews in Ultimate x64

Hey guys,
I have W7 Ultimate x64.
It's got a problem with previews. This started happening since 3 or 4 days. In one of the user accounts on my PC, I am not getting the previews of any image file(all image file formats JPG, PNG etc) at all. No previews of any folders, video files too. Basically all the forms of previews have got disabled. This is happening in only one user account. In the other, it's working fine. I searched in google and looked tens or twenties of threads but all suggested unchecking 'Always show icons, never thumbnails'. It's already been unchecked. I tried restore defaults in folder options, but no luck. Also, I tried changing the setting through 'Visual Performance' setting. No help. I even downloaded the registry file for enabling thumbnails. No help. I tried 'restore defaults' in AMD Catalyst Control Center. Didn't help. Moreover, it shouldn't matter as it's working fine in the other account.
I am getting the same effect of no previews that happens when 'Always show icons, never thumbnails' is checked. But here, it is unchecked. So, any idea what I can do? Thanks in advance.

Here are the pics of the previews

It got fixed. I don't know what exactly happened. I ran tune up 1 click maintenance along with various other methods and may be tune up fixed the problem.