Hello! I registered here just to indicate this problem really occurs, and it is more serious than just the language settings.
Two days ago AvastUI (free 5.0 on W7 Pro x64) died on launch with the same message ("Failed to load language dll [1033\UILangRes.dll]"). My installed language pack is Russian, which is 1049. I tried to do Windows System Restore to a point when it was still working, but it didn't help. I tried to install the latest version of Avast, but it didn't help either. Then I tried to make System Restore again and it failed, but it uninstalled part of my software, so it was kind of incomplete action - far worse than "all or nothing" behaviour you usually expect from it. So I tried to roll back this incomplete restore, and it failed to roll back! My system got stuck in inconsistent state! And Avast itself became inconsistent and didn't launch anything, reporting the inconsistency instead. It was a hell of a night, I tried to fight it different ways until I realized the fact that the two points of System Restore differed in that they had different versions of Avast - 5.0 and 5.1. I removed Avast 5.1 from the Control Panel, installed Avast5.0 back again, and then finally made a clean system restore.
BTW, that's another problem to report: Windows System Restore works good if Avast is not affected, it works good between any version of Avast and no Avast and vice versa, but it makes huge problems between Avast 5.0 and 5.1 and vice versa. Consider if anyone wanted to restore his system for some reasons not related to Avast, but if by a coincidence he had updated Avast in the meanwhile... nothing to envy in such situation. I guess it should be taken into account.
After recovering my system I tried to remove Avast 5.0 in safe mode and made a fresh install of 5.1 with both 1033&1049 language packs. It seemed to work first, but after a reboot it showed everything in English, forgot my settings and failed to change them. I tried to switch between 5.0 and 5.1 in different variations, but each of them worked properly only until the first reboot. So, while still running 5.0 after n-th install but BEFORE reboting (to stay protected), I downloaded the Avast removal tool thinking that making a cleaner reboot could help things. While it was being downloaded (or, maybe, when the download was complete and Avast tried to scan the file - I didn't catch that very moment), the AvastUI crashed - for the first time in my life. But, finally, I made a clean removal, installed Avast5.1, and it seemed fine - or maybe I was already so tired that I forgot to reboot once again. I ran a full system scan on bootup. Perfectly clean. That was the time to have at least some sleep, which I did, thinking that the problem is finally solved. Ran chkdsk also (no problems found).
This evening I booted up and noticed that Avast is showing in English again. And, yes, all my settings were forgotten, and they didn't change when I tried to. But what was really bad, that none of the shields was running, and Avast didn't tell anything about that! I wouldn't know that if I didn't click on Realtime Shields in UI. And none of them could start, reporting they were "unreachable". So we get that everything seemed fine, but the system was actually unprotected, and the user wouldn't notice if not looking intentionally. That condition could pass totally undetected for the users who installed Avast with the default language pack, and maybe that's actually the case with some English-speaking users right now.
My wife's laptop with WinXP and Avast5.0 (installed from the same executive that the Avast5.0 on mine) has been fine all the time, so I thought of two possibilities - a W7 update that conflicted with Avast (unlikely, because I've not installed any Windows updates except for the virus definitions for Windows Defender), or a virus that infected my machine (also unlikely that Avast could pass it through, but worth checking anyway). I downloaded DrWeb CureIt and ran a quick scan. All clean. And only then I thought: where should the .ini file be located, if it is not in the Program Files\Alwil Software\Avast5 ? It was not there on my wife's laptop so it should not be there. And then I found this thread.
C:\ProgramData>cacls "c:\programdata"INGEBOUWD = BUILTIN
c:\ProgramData NT AUTHORITY\SYSTEM:(OI)(CI)F
MAKER EIGENAAR = MAKER OWNER
Just the same, substituting Russian translation for Dutch.
I tried to add BUILTIN\Users to make it like that:
c:\ProgramData NT AUTHORITY\SYSTEM:(OI)(CI)F
It failed on Adobe and Alwil Software\Avast5 folders. Well, with Adobe we shall see what we shall see some other time, and with Alwil Software\Avast5 the problem was the Avast self-protection. I turned it off and succeeded to inherit the read permissions from the parent folder. Going to reboot now and look what happens.
Still there is one question hanging:
But who deleted the Read access right from the directory?
seems to be IS
didn't run RAN
DrWeb CureIt FULL system scan)*. No Windows updates except for the WD virus signatures. I myself haven't even known until today that the Users\All Users hidden system folder is actually a symlink to C:\Programdata which I never have noticed before, and I never changed access rights on any hidden or system folders (I keep them invisible most of the time). The only software I installed in the meanwhile was Presonus Studio One Artist which I installed from a Presonus DVD and legitimately activated online; moreover, it doesn't use C:\Programdata at all! What could be the case?!
* updated the message the next day (shown in BOLD ORANGE