When I start my desktop it gives me an error about
How to get rid of it?
I found nothing when i started regedit.exe and searched (F3 or CTRL+F) for BackgroundContainer.dll
This was a malware. It was removed by your AntiVirus Scanner, but the registry entries are still present to start the malware at startup.
To be safe, make a full scan with an AntiVirus Scanner like Microsoft Security Essentials/ Defender and also scan your PC with Malwarebytes' Anti-Malware.
If you can find nothing in the registry, download and run Autoruns from sysinterals and look here for an entry " BackgroundContainer". Look under
This question is protected to prevent "thanks!", "me too!", or spam answers by new users. To answer it, you must have earned at least 10 reputation on this site.