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Question Audio crackling and dropouts, system slowdown while downloading, high DPC latency.

Sep 14, 2021
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I don't know if you're allowed to post an issue that is solved but I spent many hours hunting this one down and Tom's Hardware always seems to come up in Google results, so this might help somebody some day.

I was suffering from very pronounced audio crackling/dropouts and a general slowdown of my entire system (sluggish response times while neither CPU, Memory, Disk nor GPU were anywhere near their limits) anytime my system had any network activity going on, like downloading something. When I would stop the download, the system would be fine again. Trying to troubleshoot this I eventually found out what DPC latency is and how to check it with LatencyMon. Needless to say I had insanely high values while downloading (I don't remember but it was something ridiculous, like over 100k and the driver was mostly ndis.sys, so network.)

After spending days reading through forum posts and articles and trying every troubleshooting step I could think of, including obvious things like checking for overheating problems, updating drivers, trying different drivers, changing out RAM and graphics card for old stuff I had lying around, disabling uncritical system components in device manager, I hadn't gotten anywhere and I was at the point where I was about to try a fresh Windows install. But then in the process of going through my files I thought why not try uninstalling any unnecessary program first. So I got rid of everything, which in the end turned out to be completely useless in itself, but it still lead me to the solution.

While cleaning up leftover folders after uninstalls I found a folder called Checkpoint in either User/Local or LocalLow, I don't remember. Windows wouldn't let me delete it. Inside it was a folder named ZoneAlarm and inside that was a single 0 byte file called fwpktlog.txt with a change date being the current time. Apparently this is a logfile for ZoneAlarm Free Firewall.

I had used ZoneAlarm's firewall some weeks ago, found out it couldn't do what I needed it to and promptly uninstalled it again. But it turns out ZoneAlarm's uninstall process is garbage, to the point that other users have programmed a ZoneAlarm removal tool (available here at MajorGeeks.com.) Long story short, after using the tool the folder was gone and so was my problem. I've been running for over two weeks now without having the issue recur.

I have no idea how that works, but my theory is that ZoneAlarm somehow, without any existing .exe or service left over, from what I could see, was still hanging around on my PC in some weird, wounded state and anytime I would download things it would do something with the network traffic and try and fail to write log files about it.

ZoneAlarm, not even once.

It would be neat if a mod could change the status to Solved.
 
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That is why it is recommended to do a restore point before adding any new or unknown program on your pc so you can simply go back to a point in time before the problems started. Just for info not criticizing you. :vip:

That seems like overkill, unless you're actually installing something sketchy. And then maybe you shouldn't be installing it in the first place. It also doesn't really help unless you notice an issue immediately and can connect it to whatever you did. I suppose you could just blindly go back to some earlier restore point and live in blissful ignorance if it fixes things, but I'd rather know what actually happened.
 
That seems like overkill, unless you're actually installing something sketchy. And then maybe you shouldn't be installing it in the first place. It also doesn't really help unless you notice an issue immediately and can connect it to whatever you did. I suppose you could just blindly go back to some earlier restore point and live in blissful ignorance if it fixes things, but I'd rather know what actually happened.
Yes that's your choice but for the average user it is smart to have restore points.