Avast will not abort scan, crippling my system!

Avast Free Antivirus / Premium Security
1

Heres the situation - this is being posted from my phone because my PC is out of commission until this gets resolved.

I started a full system scan last night around 8. At around 11, everything on my PC ground to a halt. Webpages won’t open, programs are sluggish and slow. I’ve seen scans slow my PC down before, but never like this. I looked at the scan- it’s at 20%. I figured I’d let it run overnight. Come back, it’s now almost 10 AM and it’s at 26% and has been stuck on the same file for as long as I’ve been watching it. I attempted to pause or stop- no response.

I had to manually reboot my PC and enter safe mode. Load up Avast, and guess what! Still at 26% on the same file. Manually ended process and rebooted it- still at 26%. I can minimize the program, so I know it isn’t frozen. But it will not stop, pause, or abort- and has literally crippled my PC. This needs to stop, immediately. I work from my computer and absolutely can not have this going on.

thanks in advance for any help.

2

What is the filename and the location ?
What is the filename and location of the last successfully scanned file ?

What exact version of avast ?
What OS/SP ?
Any other security (related) software installed (or was there) ?

3

I’m often noticed Avast doing something really weird when scanning. It really does look like it’s entering a deadlock, posting tasks to the DPC queue, which in turn spawns more tasks on that queue, in adfinitum, meanwhile the PC grinds to a screeching halt, with even the mouse pointer being sluggish.
Only solution I’ve found was to simply kill the “Avast Service” process from the task manager.

This of course halts all of Avast, but you’ll feel like you have a whole new machine, without Avast eating up your resources.

4
Only solution I've found was to simply kill the "Avast Service" process from the task manager.
That is only possible if avast self defense is disabled. ;)
5

So they spent resources protecting themselves from us protecting our PC’s from them?

Sounds like they are a shoe in for US police forces.

6
So they spent resources protecting themselves from us protecting our PC's from them?
some Malware can turn off your AV ...
7
So they spent resources protecting themselves from us protecting our PC's from them?
No, the software is (as Pondus indicated) trying to protect itself from getting infected and become useless.

But let’s get back to the OP’s problem and see if we can help him/her.