updates possible only on admin account why ??

[bcool]

Yes the error code was explained but I suspect that the explanation wasn't comprehensive enough. 
I only say this because none of what has already been mentioned here relating to 0426 seems to adequately address my situation.  On the other hand, we could add to the list that this error code indicates that a manual update request is being blocked. 
I can surely attest to that. 

Anyway, thanks so much for your help.  It is much appreciated.

[bcool]

Because Avast (HOME) works what appears to be flawlessly from a limited user account save for manual updating, I have to admit that uprooting the reason I can't update at will has loss urgency for me.  I still suspect when the smoke clears it will be revealed that this was by design all along.  Regardless, I'm content with Avast's faithful automatic updating from my limited user account.  I have no other complaints.  Thanks again.

[HA Nut]

Curious... 

Has there been any news on this front from the avast! support team/programers? I gave avast! Home a trial last night/this morning and manual definition updates still do not work from a limited user account in XP.

From a PC safety standpoint, I feel that connecting to the web as a limited user is important and an antivirus should be able to update either automatically or manually (depending on specific situations.) In my case, I am on very slow dialup. I just cannot allow applications to run auto updates. If I did, I would never be able to do anything else when I'm connected...

[Lisandro]

I gave avast! Home a trial last night/this morning and manual definition updates still do not work from a limited user account in XP.

I've tested few minutes ago and have no problems into a limited user account.
Into the Administrator account, try to change the logon account for avast updates to administrator account.
In services control panel display properties of avast! iAVS4 Control Service, switch to LogOn page, and enter administrator account and password. Restart service to take effect on changes.
You can try setting avast! Antivirus service logon too.

[HA Nut]

I made the changes to the 2 services you noted but no joy.  :'(  Still unable to update manually as a limited user (admin works fine as it has all along.)

Based on my tests, I'm thinking it must be a permissions issue with a folder and/or some file(s). If I change the limited account to an admin, it can manually update fine...

[Lisandro]

I'm thinking it must be a permissions issue with a folder and/or some file(s).

Did you install avast in the default folder?
If you follow...
1. Uninstall avast from Control Panel first.
2. Boot.
3. Use Avast Uninstall for complete uninstallation.
4. Boot.
5. Install again from the scratch, will it work?

[HA Nut]

Did you install avast in the default folder?
If you follow...
1. Uninstall avast from Control Panel first.
2. Boot.
3. Use Avast Uninstall for complete uninstallation.
4. Boot.
5. Install again from the scratch, will it work?

The installation was the typical default setup. I made no customizations and installed the files to the regular, default folder.

I have installed the program 3 or 4 times. After each trial, I reverted back to the drive image I had created prior to the installation.

I have not tried to do a second, clean install. I will try that and get back.

(FWIW, the AV, antispyware and antitrojan I have been using all update fine (both automatically and manually) under the limited user account.)

[Lisandro]

(FWIW, the AV, antispyware and antitrojan I have been using all update fine (both automatically and manually) under the limited user account.)

Which are these programs that you're using?

[sergofun]

I'm thinking it must be a permissions issue with a folder and/or some file(s). If I change the limited account to an admin, it can manually update fine...

Hi! HA Nut, I think you are right. At admin account I've gave some permissions for limited account to "ALWILL Software" folder. Now I manually update avast! at limited account.

[Lisandro]

Hi! HA Nut, I think you are right. At admin account I've gave some permissions for limited account to "ALWILL Software" folder. Now I manually update avast! at limited account.

But take care, you've reduced the security level of that folder (and so, of avast in general).
Generally, it would be enough to correct this with a new installation.

If avast! is run from non-admin account, it does spawn the setup process using the service with LocalSystem rights. That brings you that it should update program without problem.
So, to sum it up: it should be possible to run whole program update from an limited user account, avast's setup was designed that way.

[HA Nut]

Update...

The programs that I have been updating manually via my limited account have been SuperAntiSpyware, Comodo BOClean and NOD32. (They can update automatically but on my slow dialup, I need to control things better. Otherwise, the PC would be updating for 10 to 15 minutes (or more) the first boot/connection of each day.)

I spent a fair amount of time tonight testing 2 more avast installs (per your recommendations.) I also installed and tested another free competitor for manual updating under a limited account.

Neither the 1st or second install of avast would manually update via the limited account. I finally tried changing the security setting for the Setup folder (under Alwil\Avast4) to "Modify" for the limited account and it then ran ok. So it is something related to permissions. But as you noted, my feeling is that even though that works, it's not something one should be doing as a permanent solution.

FWIW, I also tested another free AV from a competitor. It was able to manually update via the limited account with no issues. (I didn't care for how it reacts with ZoneAlarm though. Always banging at the door, so to speak.)

Anyway, I'm kinda spent from all the tests. I'll probably sit things out for a while and test some later builds, which will hopefully work out better...  Thanks for the ideas!

[sergofun]

Tech, thanks for explaining

[Lisandro]

I finally tried changing the security setting for the Setup folder (under Alwil\Avast4) to "Modify" for the limited account and it then ran ok.

Uninstall avast, boot, use the uninstall tool, delete the avast folder if it remains there.
Boot and install again.
This way, installing from the scratch, the permissions will be set correctly.
Other way, you're lowering your computer security: a virus could destroy avast installation.

FWIW, I also tested another free AV from a competitor. It was able to manually update via the limited account with no issues. (I didn't care for how it reacts with ZoneAlarm though. Always banging at the door, so to speak.)

I'm absolutely sure that avast updates from a limited account IF it is correctly installed.
I have 3 computers running this way. All of them update through the limited accounts. XP SP2 by the way.