Hallo,
vielen Dank im Voraus für Ihre Hilfe!
Ich habe Ihre Anweisung befolgt und hier ist meine Datei mit den Basis-Logs des Malware-Scans:
https://forum.avast.com/index.php?topic=102616.0
Wir brauchen auch die Farbar logs (FRST.txt und Addition.txt)
Oh sorry, hier kommen sie!
Ein Malware-Experte ist informiert, bitte etwas Geduld…
Willkommen im Forum,
Asyn
What problems are you experiencing ?
CAUTION : This fix is only valid for this specific machine, using it on another may break your computer
Open notepad and copy/paste the text in the quotebox below into it:
CreateRestorePoint: Reg: reg delete HKLM\SOFTWARE\Policies\Microsoft\Windows\IPSec\Policy\Local /f Reg: reg add HKLM\SOFTWARE\Policies\Microsoft\Windows\IPSec\Policy\Local /f RemoveProxy: EmptyTemp: CMD: bitsadmin /reset /allusers
Save this as fixlist.txt, in the same location as FRST.exe
https://dl.dropboxusercontent.com/u/73555776/FRSTfix.JPG
Run FRST and press Fix
On completion a log will be generated please post that
THEN
Please download AdwCleaner by Xplode onto your desktop.
[*]Close all open programs and internet browsers.
[*]Double click on AdwCleaner.exe to run the tool.
[*]Click on Scan.
[*]After the scan is complete click on “Clean”
[*]Confirm each time with Ok.
[*]Your computer will be rebooted automatically. A text file will open after the restart.
[*]Please post the content of that logfile with your next answer.
[*]You can find the logfile at C:\AdwCleaner[S0].txt as well.
Thank you for supporting me!
The main problem is, that my firefox-browser is very slowly and everytime I open it, an error message from avast appears. I´ve attached a screenshot of it in this message, just as the generated fixlog-file after running the FRST-fix.
P.S.: Sorry for my bad english 
… and here is the content of the logfile from AdwCleaner:
AdwCleaner v5.025 - Bericht erstellt am 20/12/2015 um 13:08:03
Aktualisiert am 13/12/2015 von Xplode
Datenbank : 2015-12-13.2 [Server]
Betriebssystem : Windows 8.1 Connected (x86)
Benutzername : Kati - K
Gestartet von : C:\Users\Kati\Desktop\AdwCleaner.exe
Option : Löschen
Unterstützung : http://toolslib.net/forum
***** [ Dienste ] *****
***** [ Ordner ] *****
[-] Ordner Gelöscht : C:\Program Files\Startfenster
***** [ Dateien ] *****
***** [ DLLs ] *****
***** [ Verknüpfungen ] *****
***** [ Aufgabenplanung ] *****
***** [ Registrierungsdatenbank ] *****
[-] Schlüssel Gelöscht : HKCU\Software\OCS
[-] Schlüssel Gelöscht : HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\FE5AE7DC-7B01-4263-A94C-B4526C276550_is1
[-] Schlüssel Gelöscht : HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Startfenster
***** [ Internetbrowser ] *****
:: “Tracing” Schlüssel gelöscht
:: Winsock Einstellungen zurückgesetzt
########## EOF - C:\AdwCleaner\AdwCleaner[C1].txt - [1041 Bytes] ##########
Run this small fix … If it does not cure the problem then reset Firefox https://support.mozilla.org/de/kb/firefox-restaurieren-einstellungen-und-addons-zuruecksetzen
CAUTION : This fix is only valid for this specific system , using it on another may break your computer
Open notepad and copy/paste the text in the quotebox below into it:
CreateRestorePoint: FF ExtraCheck: C:\Program Files\mozilla firefox\defaults\pref\itms.js [2014-10-08] EmptyTemp: CMD: bitsadmin /reset /allusers
Save this as fixlist.txt, in the same location as FRST.exe
https://dl.dropboxusercontent.com/u/73555776/FRSTfix.JPG
Run FRST and press Fix
On completion a log will be generated please post that
Now there are three error codes instead of four ;D
Okay, I will try the reset!
Yeah, that was it!
Thank you very much and have a nice Christmas 
Subject to no further problems 
I will remove my tools now and give some recommendations, but, I would like you to run for 24 hours or so and come back if you have any problems
Now the best part of the day ----- Your log now appears clean 
A good workman always cleans up after himself so…The following will implement some cleanup procedures as well as reset System Restore points:
Remove tools
Download and run Delfix
Select the options as shown
https://dl.dropboxusercontent.com/u/73555776/delfix.JPG
Now that you are clean, to help protect your computer in the future I recommend that you get the following free programmes:
CryptoPrevent install this programme to lock down and prevent crypto ransome ware
https://dl.dropboxusercontent.com/u/73555776/CryptoPrevent.JPG
Update and run weekly to keep your system clean
Click on the link above to be taken to Unchecky.com
click the very large Download button.
click Save
Click Open folder
Right click on the Unchecky_setup and choose to Run as Administrator
Once open click the Install button.
Then click on Finish
Unchecky is now installed and will help you keep unwanted check boxes unchecked, this is a fire and forget programme
It is critical to have both a firewall and anti virus to protect your system and to keep them updated.
To learn more about how to protect yourself while on the internet read this little guide Best security practices Keep safe 