my free avast antivirus not working

i have downloaded the free antivirus and have used it just fine in the past , now i am getting a error when i started it up saying another antivirus and two may conflict and so avast is running in passive mode , i have checked and have no other antivirus , i have antimalware bytes .
when i try to open the interface of avast it just comes up like a blank page where the settings etc. all are its just a big square blank area of white.
I HAVE A WINDOWS 7 QUADE CORE HP LAPTOP
can someone please help me get this program going again ??

i have antimalware bytes
The name is Malwarebytes Antimalware ;)

Try uninstall avast with this (read instructions) >> https://www.avast.com/uninstall-utility
Then try install again

IF you have used any previous AV programs make sure thay are removed according to vendors instructions / removal tools

Removal tools:
https://singularlabs.com/uninstallers/security-software/
https://support.avast.com/en-eu/article/Uninstall-other-antivirus

okay i followed instructions downloaded the avast clear to my desktop then restarted pc in safe mode (i did it without internet) and used admin install and it ran for a long time then gave this error :avast antivirus installer is unable to continue because the installer is corrupted or is forbidden to run on this machine. reason 2.
(0x000000002) the system cannot find the file specified.

Update to the latest version (17.8.2318): https://forum.avast.com/index.php?topic=210678.0
Regarding Avast & MBAM, see: https://forums.malwarebytes.com/topic/200324-exclusions-for-avast-users/