Built-in elevated administrator account has access denied

So... after many years having this problem, I decided to post for some help. I've been using this computer (Acer Aspire with Windows 7 Home premium x64 on an Administrator account) without issues for quite a while. One day, like two years ago, I noticed something weird while using Calibre (the virtual library software): the program was not able to save or edit files because it was not run as administrator. This was odd, because it was not supposed to work that way, and it worked fine without admin privileges before, but then I got used to using it as administrator. After that, I noticed that other programs were having this issue as well (Steam, Spotify, many others) and I gradually integrated into my workflow the use of programs as administrator... until I got fed up recently.

I've been looking for help and answers but it seems no one or almost no one has this exact problem, so I thought I'd better ask for help.

Just to be clear, this has nothing to do with UAC. It is just that if, for example, Spotify is running without admin privileges and it wants to update, the update fails. I have to restart the program as administrator and then it can install whatever it wants. Every installation I do has to be done through rightclick->run as administrator, as an unelevated installation file will fail.

I've recently tried to take ownership of my C:\ drive, to no use. I also tried resetting the files and folder permission to default with the use of

Code:

secedit /configure /cfg %windir%\inf\defltbase.inf /db defltbase.sdb /verbose

also to no avail.

I have just learned about the existence of the hidden built-in elevated administrator account in Windows 7, so I figured that using this account may help me regain ownership to my normal administrator account or to the administrators group, however, while doing this, an error message pops up and says that Access is denied. What on Earth is going on???

Good method to mess up Windows install once and for all Stop messing with the permissions imho.
It may very well be a registry issue.

Did you try to make another administrator account and see if programs work well with it?

Hhehe, you're right, I should have probably come here sooner :P And no, using another Admin account did not solve the problem :S

You said it is not UAC, but did you actually try disabling UAC (as a diagnostic step at least)? That should force all programs to run as admin.

Also try this https://support.microsoft.com/en-us/kb/968003