Struggle for Permissions (User Profile Service *bricked*)

sup everyone, first time postin here, I'll try to make my post as informative and entertaining as possible!
for a TL:*DR version, scroll down to the bottom...

What happened so far:

My PC, after succesfully restarting from sleep mode had a stroke, stuff would load extremely slow until a few seconds later all programs (chrome, paint, steam, whatever) started spamming my screen with "Program doesnt respond, shutting down" messages, with the last message being "Windows encountered a critical error and will be shut down in one minute" without any "OK" or "shut down now" button.
To me that error message sounded like something caused by Malware, so I was kind of expecting a black screen with russian letters popping up telling me to pay some dosh to unlock my pc :*D
...but no, windows would simply try to reboot and fail in the process without any BSOD or error messages, over and over again.
At some point I decided to run a System Repair (accessing through F8 after safe mode wouldnt boot either) and it took my PC whole FOUR hours to finish it... that's where the fun began.
Windows managed to boot, yet i would get stuck on a black screen (BEFORE the User Profiles screen) with only my mouse cursor (at least i could move it!)
Not even the windows install DVD would work! It simply wouldn't load the Installation manager GUI, leaving me with the pretty blue default windows screen...
After googling on my Laptop for hours i came accross a post including this command:
cacls D:\Windows\System32 /E /T /C /G everyone:F
Hoping for the best, i tried it using cmd during the System Repair Mode and it actually worked (kinda).
Now the blue background would appear after booting Windows, yet my User accounts wouldn't, instead my HDD was going insane, with the screen occasionally turning black for a split second and after a minute or two, staying black, apparently the Malware was doing the best job possible of keeping me away. Safe Mode still wouldnt work either at this point, so i repeated the previous cacls command, but instead applied it to the whole Windows and Users folders and it actually worked! (...kinda)
I can now see my User Profiles, yet clicking on shows the infamous "User Profile Service failed to load" error.
After that, i tried safe mode again... and it worked! (for real this time) but here's the odd thing, instead of automatically logging into the default Admin account, i ended up in the Account selection screen from before! But this time, logging in worked and I could finally see my desktop!
Next, i followed THIS tutorial.
In fact, my User account had the .bak ending, deleted it and replaced the values, however that didn't help.
Now comes the crazy stuff, even creating a completely fresh account with Admin rights doesn't do anything, can't access it either!
So now my assumption is that the accounts themself are fine, however something is blocking the User profile Service from properly working (apprently it does under safe mode)
Cleaning with Kaspersky and MalwareBytes no Malware was found though... (guess i deleted it while i had the HDD plugged in into my laptop while i was removing stuff)
So now i am left with the hunt for wrong registry entries and missing permissions... but reading through various threads i am starting to run out of solutions to try out, that's why i am here, for the first time in my life, unable to fix a PC myself, asking on a forum for help, how embarassing :*D ...

P.S.: NO. i DON'T have any system restore points and i am NOT going to give up and reinstall my PC-imperium, which i was building and customizing over the past years without a proper fight! ...else i wouldn't even bother with all of this :*D

TL:*DR
-malware(?) kills permissions for a proper system start
-system repair nets a black screen (before user accounts popping up)
-assigned rights to important folders using cmd during system repair mode
-edited registry to fix user profile
-can choose and enter user profiles when starting safe mode (when it should automatically login into the default admin)
-new conclusion: a service related to user profiles still has no permissions OR something is completely bricked

UPDATE: just finished running sfc /scannow, says everything's fine... as if
UPDATE2: unlocking the hidden admin account of my windows 7, i actually managed to succesfully log in into it without using safe mode, my regular (admin) account still doesn't work, other, new created admin/standard accounts don't work either, the newly created user profiles don't even have a registry entry under ProfileList, things gettin crazy

gabbagab said:

yeah i will consider a repair install as a last solution, even though it is basically the same as a full format and clean install with the User folder being backupped on an external drive (or am i completely wrong here?)

I've never done a Repair Install, so i can't answer for sure.
The tutorial says it preserves programs and SYSTEM drivers ...

I use System Backup Images, and use those when i want to recover, or back-out changes i don't want ...
I don't store User data on the [C] partition, so i don't have to be concerned with losing any user data when i restore an image.

You can ask questions in the Repair Install tutorial.

hth