@Arne08
Hello and wellcome to avast. 
[*] I will be working on your Malware issues this may or may not solve other issues you have with your machine.
[*] The fixes are specific to your problem and should only be used for this issue on this machine.
[*] If you don’t know or understand something, please don’t hesitate to ask.
[*]Please refrain from making any further changes to your computer (Install/Uninstall programs, delete files, edit the registry, etc…)
[*] Please DO NOT run any other tools or scans whilst I am helping you.
[*] It is important that you reply to this thread. Do not start a new topic.
[*] Your security programs may give warnings for some of the tools I will ask you to use. Be assured, any links I give are safe.
[*] Absence of symptoms does not mean that everything is clear.
Step#1
Please download Malwarebytes AntiRootkit and save it to your desktop.
http://www.malwarebytes.org/products/mbar/
Full instructions how to use MBAR
http://www.bleepingcomputer.com/virus-removal/how-to-use-malwarebytes-anti-rootkit
Please note: This is a beta version so please be sure to read the disclaimer and note of it.
[*] Unzip/unrar MBAR in a folder to your Desktop
[*] Open the folder where the contents were unzipped to run mbar.exe
[*] Click on Next > then on Update button to download fresh definitions.
[*] When database updates click Next
[*] In the following window ensure “Targets” scan for Drivers; Sectors; System are ticked. Then select “Scan button”
[*] If an infection/s are found ensure “Create Restore Point” is checked, then select the “Cleanup Button” to remove threats.
Or if you are sure any entries should not be kept, just untick them. A list of infected files will be listed.
[*] The Clean up procedure will be Scheduled for process.
[*] When complete pop-up will show you. Select the Yes button and the system should re-boot to complete the cleaning process.
Please attach the two following logs from the mbar folder:
system-log.txt
and
mbar-log-year-month-day (hour-minute-second).txt.
Step#2
Download TDSSKiller and save it to your desktop
Execute [b]TDSSKiller.exe[/b] by doubleclicking on it.
[*] Press Start Scan
[*] If Suspicious object is detected, the default action will be Skip, click on Continue.
[*] If Malicious objects are found, select Cure.
Once complete, a log will be produced at the root drive which is typically C:\ ,for example, [b]C:\TDSSKiller.<version_date_time>log.txt[/b]
Please post the contents of that log in your next reply.
Step#3
Download ComboFix from here and save it to your Desktop.
If you are unsure how ComboFix works please read this guide carefully.
note: ComboFix must be downloaded to your Desktop.
Temporarily disable your AntiVirus program.
If you are unsure how to do this please read this or this Instruction.
How to disable avast:
[*]Right-click on the avast! icon in the lower right corner of the screen and choose Open Avast! User Interface.
[*]In the window that opens on the top right corner, click Settings.
[*]In a new window that opens, choose the option Troubleshooting, Uncheck Enable avast! self-defense, and click OK.
[*]Right-click on the avast! icon in the lower right corner of the screen and select avast! shield controls .
[*]In the menu that appears, choose Disable Permanently. When you are prompted to turn off security, click Yes.
Note: Do not forget to turn on this option after the cleaning.
Run ComboFix. Click on I Agree!
ComboFix will check if there is a newer version of ComboFix available.
Click Yes if prompted to download.
ComboFix will display DISCLAIMER OF WARRANTY ON SOFTWARE.
Click Yes to allow ComboFix to continue.
If Recovery Console is not installed, ComboFix will offer download & installation.
Click Yes to allow ComboFix to install Recovery Console.
Note:Do not mouse-click Combofix’s window while it is running.
If you see a message like “Illegal operation attempted on a registry key that has been marked for deletion” just restart computer once more.
When the tool is finished, it will produce a log report for you. (typical location: C:[b]ComboFix.txt[/b] )
Attach log reports ( ComboFix.txt) back to topic.
