system
1
I have been a long time avast user. Just recently I have updated from Avast 8 to 9 using the antivirus built in updater and once the update gets installed and restarted I could see the new avast working fine. Then the subsequent reboots made things miserable, Avast UI fails to display and I couldn’t see the icon in system tray and also the Desktop gadget shows no sign. If I try clicking some folder and initiate a scan it reports the AvastUI.exe is not loaded but when I peek into taskbar I could see AvastUI.exe running. All this weird things I have been seeing after updating avast. So I went ahead and used the uninstaller and performed repair and it didn’t helped and then went ahead and removed and installed it again. After doing the reinstall I could see the avast working fine and again on another reboot things are back to worse and the same AvastUI issue happens now. What is wrong here any clue
Avast Free Edition
Windows 7 Home Premium (SP1) 64Bit
Do you have any other security software installed?
If not, then it’s probably best that you use the avast uninstall utility for all versions of avast that you have used to make certain all old program files are removed.
First, download to your desktop the avast 2014 free version from here → http://files.avast.com/iavs9x/avast_free_antivirus_setup.exe
Then, follow the instructions here → http://www.avast.com/en-us/faq.php?article=AVKB10#idt_02
After this, reinstall avast.
system
3
Apart from AVAST I have Malware Bytes ANTI-MALWARE.
As per your direction I did the uninstall from safe mode and did a install. Will keep an eye and see how it works now
If still I get any problem how do I revert back to Avast 8 which was working great without any problem
MalwareBytes, Free or Pro, plays well with avast.
If you did not save your v8.0 set-up file you can download v8.0 from filehippo.com just be sure you select the desired version from the right side column.
Don’t forget to use the avast uninstaller for a clean install. 
system
5
I have MalwareBytes ANTI-MALWARE Free edition only.
As for the problem is concerned after reboot I am back to the same issue where avast fails to show UI and also fails to perform scan which is not at all healthy, so reverted back to avast 8 and moving peacefully.