Windows Explorer Crashes On Right Click And Opening Folder

About since I installed jdownloader this afternoon (and afterwards removed "search protect" with AdwCleaner and Malwarebyte Anti-Malware), my Windows explorer regularly freezes.

It does so whenever I do a right-click on any folder or disk or on the free space inside a folder or disk. It also crashes whenever I open folder, which I have not recently opened or to which I added a big file (bigger than about 1 MB) recently. I could open some folders since this error came up but after adding a file to them, this is not possible anymore. Windows explorer being able to open some folders is probably due to it cashing/indexing some information. I can read everything using cmd (cd & dir) and execute files directly though.

In safe mode Windows explorer works fine.

What I did so far:
- Following this guide (Right-click is slow or weird behavior caused by context menu handlers) I removed all the handlers in the registry in HKCRAllFileSystemObjectsshellexcontextmenuhandlers, HKCRFoldershellexcontextmenuhandlers and HKCRDirectoryshellexcontextmenuhandlers. Deletion of one handle in HKCRDirectoryshellexcontextmenuhandlers called "WorkFolders" only produces an error. I therefore could not delete this one. It did not work. Afterwards I recovered the registry keys.

- I used system recovery to switch back to a state from the day before yesterday.
- I tried disabling all the files in auto-start using the task-manager with no improvement.
- I ran "sfc /scannow", which told me there were some files it was unable to repair. I digged into the log and found the file sfc talked about. The file was completely missing. I got a copy from my notebook and managed to copy that file into the folder. But it didn't work.

What's more, I could not rerun sfc to see if the sfc-error persisted, because my computer froze during login after the restart (during which I also installed some minor Windows updates) and I had to force a restart. This brought up a bluescreen on the first two following restarts. On the third one, recovery came up and I chose automatic repair. After that the system could start again, but "sfc /scannow" now throws an error saying "There is a system repair pending which requires reboot to complete. Restart ...". I tried running "dims.exe /image:C: /cleanup-image /revertpendingactions" in the recovery console, which threw an error saying that it was unable to complete. I also tried rerunning the startup repair, which told me it was unsuccessful. sfc is still not running.

Additionally, and I think this started at about the same time, Avira cannot start its real-time protection anymore. I don't get any useful information out of it, just that it encountered some error. I reinstalled it twice, to no avail.