Avast 4.8 Home. Scan seems to stop

Whenever I configure my virus scan to ‘thorough’ mode, there comes
a point when the scan seems to stop. The computer activity light continues
to flash, but the scan doesn’t progress beyond a certain file. Eventually
I have to stop the scan and start up again in ‘standard’ mode which is
the only way it will complete.

If someone could advise me what’s going wrong, I would appreciate it.

What is the file reported as being scanned at the time? More especially what is the file type?

I ask because we have seen reports of very long scan times that I have reproduced (that appear to hang but are just taking a long time) on, for example, large (> 1-2Gb) .avi files.

Yes, big files can take looong time to scan, so it seems lika avast is freezed, but it isn’t.

Thorough is also by its design very thorough and perhaps a little overkill for routine use, were a Standard scan without archives should be adequate.

Archive (zip, rar, etc.) files are by their nature are inert, you need to extract the files and then you have to run them to be a threat. Long before that happens avast’s Standard Shield should have scanned them and before an executable is run that is scanned.

I have only ever done a Through Scan with Archives once shortly after installation just to ensure a clean start state, but with XP for example avast will do a boot-time scan after installation if you select it, this I believe will be quicker and reasonably effective. Like everything in life things are a compromise.

I installed Avast personal edition on my Daughters computer yesterday. I thought I would be done and gone in a half an hour. As soon as it installed it found a trojan, and launched into a bootup scan. As described above in an earlier post, it sat on 1% forever, found the trojan where I made my decision to quarantine, and went to 2% forever until it found another place the trojan had infiltrated and so on. Well about an hour and a half later it found the trojan 57 places and finished. Good job. The only down side was that I shot my day. ;D

Well there is an option in the list (6 I believe, see image) Move all to chest, which I presume would have saved some time.

Personally I would do as you have done and process them interactively (I like to know exactly what is going on in my system), this however, after this initial road hump it should be much smoother should you choose a boot-time scan in the future.

Yes, you are absolutely correct. You will be aware that the current scanned file display isn’t the best
as it’s rather truncated. However, I was able to discern the directory and 'lo and behold, the
directory contains very large avi files, some of which are in excess of 1 Gb.

I am currently doing another ‘thorough’ scan and sure enough, it’s stopped on the same AVI
directory. This time I’m just going to let it run in order to see if it will eventually resume.

I’ll post the results.

.avi scans can seem to take forever in avast but they do progress although at a “watching paint dry” pace (personally I exclude avi scans by avast - I am not prepared to allow my scans of the drives containing them to take days to complete).

Well, the thorough scan took around 20 hours in all and it came up with a single infected file. It took ages to
scan my Ghost Backup folder which is a repository for huge files.

Having tested out the thorough scan, I think I’ll use the standard one from now on.

For me, as I said once was enough to ensure a clean start state and if you suspect anything.

As Alan said you could exclude the avi files from scans.

I also exclude the folder where my drive image back-ups are, I do a weekly drive image back-up but before that I do all my scans so there isn’t much likelihood of infection in the drive images and certainly not in executable files, archives being inert (have to be unpacked first) they don’t present a high risk if they did happen to be infected.