If possible then open Avast GUI and in settings > troubleshooting disable self defence

If this is not possible then run the following fix from safe mode

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: HKLM\...\Run: [AvastUI.exe] => C:\Program Files\AVAST Software\Avast\AvastUI.exe [5515496 2015-05-11] (Avast Software s.r.o.) ShellIconOverlayIdentifiers: [00avast] -> {472083B0-C522-11CF-8763-00608CC02F24} => C:\Program Files\AVAST Software\Avast\ashShell.dll [2015-04-25] (Avast Software s.r.o.) BHO: avast! Online Security -> {8E5E2654-AD2D-48bf-AC2D-D17F00898D06} -> C:\Program Files\AVAST Software\Avast\aswWebRepIE.dll [2015-03-23] (Avast Software s.r.o.) FF Extension: Avast Online Security - C:\Program Files\AVAST Software\Avast\WebRep\FF [2012-06-15] CHR HKLM\...\Chrome\Extension: [gomekmidlodglbbmalcneegieacbdmki] - C:\Program Files\AVAST Software\Avast\WebRep\Chrome\aswWebRepChrome.crx [2015-03-23] S2 avast! Antivirus; C:\Program Files\AVAST Software\Avast\AvastSvc.exe [343336 2015-04-25] (Avast Software s.r.o.) S3 AvastVBoxSvc; C:\Program Files\AVAST Software\Avast\ng\vbox\AvastVBoxSVC.exe [3207800 2015-04-25] (Avast Software) R2 aswHwid; C:\Windows\system32\drivers\aswHwid.sys [24144 2015-04-25] () R2 aswMonFlt; C:\Windows\system32\drivers\aswMonFlt.sys [74976 2015-04-25] (Avast Software s.r.o.) R1 AswRdr; C:\Windows\system32\drivers\aswRdr.sys [55200 2015-04-25] (Avast Software s.r.o.) R0 aswRvrt; C:\Windows\system32\Drivers\aswRvrt.sys [49904 2015-04-25] () R1 aswSnx; C:\Windows\system32\drivers\aswSnx.sys [787760 2015-04-25] (Avast Software s.r.o.) R1 aswSP; C:\Windows\system32\drivers\aswSP.sys [428120 2015-06-27] (Avast Software s.r.o.) R1 aswTdi; C:\Windows\system32\drivers\aswTdi.sys [57888 2015-04-25] (Avast Software s.r.o.) R0 aswVmm; C:\Windows\system32\Drivers\aswVmm.sys [209048 2015-04-25] () R2 VBoxAswDrv; C:\Program Files\AVAST Software\Avast\ng\vbox\VBoxAswDrv.sys [220752 2015-04-25] (Avast Software) 2015-07-05 02:32 - 2015-07-05 02:32 - 00000000 ____D C:\ProgramData\Microsoft\Windows\Start Menu\Programs\AVAST Software 2015-07-05 02:30 - 2015-04-25 12:39 - 00291312 _____ (Avast Software s.r.o.) C:\Windows\system32\aswBoot.exe 2015-07-23 10:47 - 2014-11-18 10:34 - 00000000 ____D C:\Windows\system32\vbox AV: avast! Antivirus (Disabled - Up to date) {17AD7D40-BA12-9C46-7131-94903A54AD8B} AS: avast! Antivirus (Disabled - Up to date) {ACCC9CA4-9C28-93C8-4B81-AFE241D3E736} Task: {73DB3B84-0974-44CB-96D1-0DA525C10E70} - System32\Tasks\avast! Emergency Update => C:\Program Files\AVAST Software\Avast\AvastEmUpdate.exe [2015-07-05] (Avast Software s.r.o.) Task: {97888E71-4A84-404F-8322-9F12D3EE1054} - System32\Tasks\{4B6713CF-D969-453E-B826-A43987C650D9} => pcalua.exe -a "C:\Program Files\AVAST Software\Avast\Setup\Instup.exe" -c /control_panel /instop:uninstall C:\Program Files\AVAST Software 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

Download Avast Uninstall Utility to your Desktop.
Download the correct version of Avast
Avast Free
Avast Pro
Avast Internet Security
Avast Premier
Disconnect from the net

[]Run the uninstall tool and accept the reboot to safe mode
[
]Once complete reboot your system
[*]Reinstall Avast