Hi, just thought I would report a possible bug.
I use webcams to monitor multimeters to read voltages on various devices.
My monitoring PC’s are Fujitsu Siemens Amilo laptops with Windows 7 Pro 32 bit installed.
For the past month or so my webcams have been showing a black screen but only on some applications.
Skype works 100% and any program that uses Java like Yawcam, works fine, I also found the program called Debut works ok, however most other programs give you a black screen.
Not sure if I can give names but eg: MyCam, Simple Webcam, WebcamViewer and many more just give a black screen.
I was just about to reformat my hard drives and start from scratch when I decided to uninstall Avast and BINGO everything sprang to life.
So how long does my Avast need to sit in passive mode as this seems a major problem now and no real answers have been given ?
https://forum.avast.com/index.php?topic=201645.msg1392144#msg1392144
Not much (usefull) info, but at least finally a reaction from avast.
What shield is causing the problem for you ?
If they are usb cams, does it make a difference if you disable the " usb checking" ?
What OS/SP ?
Hi Eddy, sorry I’m an old guy so don’t fiddle with shields or anything but will try whats’ been suggested.
All I know is if I uninstall Avast everything works great which is what I have done on the laptops.
On my development desktop PC I’ve got Avast in Passive mode.
Yawcam btw works tottaly different to any other webcam app in that it uses Java as it’s GUI.
I develope in C++ for over 30 years now and every program I’ve written for webcams do not work unless I remove Avast.
I did try AVG before I made any post but that too did not work.
I’ll just wait till Avast fixes the problem then I’ll enable it again.
Oh btw as I said, I use Win7 Pro 32 bit + Sp1 with all latest updates on all computers.
** Edit **
Ok I tried the Shields and with all 4 turned off and a reboot, the problem is still there.
I do not know how to disable the ‘usb checking’ as you suggested.
Btw, I’m running Avast version 2294 but the problem was there with 2291 also.
No worries about being a “old guy”.
I’m 50 
And about using c++…
Did you tried things while using another compiler ?
I’m still programming in BASIC and all my applications never have a problem 
LOL, my son is nearly 50
I also tried compiling with MinGW, same story.
Here is a test app I wrote for testing.
I can mail you the source if you like, it’s in C++Builder6 format.
http://www.proasm.com/files/other/CamTest.zip
I found a way around the webcam black screen problem.
Set Avast into passive mode, it will ask you for a reboot.
After it has rebooted, switch passive mode off, it will now not ask you to reboot.
Everything works great.
Basically everytime you shut down your pc set Avast in passive mode before doing so
I bet your son doesn’t look as good as I do ;D
Seems like a bug in avast to me.
It doesn’t make sense (at least not to me) that you have to reboot if you set avast to passive mode but not if you start avast again.
Logic says avast should simply stop the real time scanning when you set it run in passive mode.
Hi,
Are you sure that the change (Passive to active) is actually and completely done without rebooting?
Ui maybe says “yes” but …in definitive?
in the same order of ideas , why avast ask you to reboot the first time (Active to Passive) , UI says you , you are in “Passive”
Does issue fixed without reboot 1st time?
Edit:sorry , Almost the same reflection as Eddy
No worries Chris.
I will forgive you (this time only) ;D
Hi Chris, ok this is what I have just done as my laptops currently have no antivirus on them at all.
I reinstalled an offline version of Avast, version 2280 which I downloaded in October 2016.
I then updated all the virus definitions.
Everything worked 100%, so I updated to the latest 2294, bingo there goes my webcam, displays a blackscreen.
So I set Avast to passive mode, it asks for a reboot, which I do, once rebooted after a minute or 2 Avast pops up suggesting I disable Passive mode, which I do, then says “we’re getting ready to actively protect your computer”, then it says “You’re Protected” and that’s that all works 100%.
The laptops run 24/7 so no problem there about shutting down
Thanks for the link Asyn, hope something happens tomorrow, will report in.
You’re welcome, please do so.
Thanks guys, new update sorted out the problem
Thanks for the great service.
You’re welcome