Yesterday my avast 4.7 home simply stopped working. The icon in left down corner simply disappeared. I tried to start it again but without any success. So I removed it from my PC and tried to instal it again. But the icon on desktop does not look like it should and when i am clicking on it an annoucement appears: "system Windows cannot locate ashAvast.exe file. I tried to instal avast antyvirus 4.7 home edition mamy times but still with no luck.
Waiting for help!!! And thanks in advance!!! ??? 
I’m not sure if this is the system tray icon (bottom right) or the desktop icon, which although useful isn’t an essential part of your avast program.
This relates to the avast ’ a ’ icon in the system tray. If this is continually happening (icon gone) it is almost certainly another security program at work.
As a temporary measure until this is resolved you can create a desktop shortcut for this file C:\Program Files\Alwil Software\Avast4\ashDisp.exe (the avast icon and interface to the providers). Right click on the file and select Send To, Desktop (create shortcut). You will need to run this after each boot until the problem is resolved.
What other security based software do you have that might block new startup entries, e.g. Spybot S&D (TeaTimer), AdAware (AdWatch), SpySweeper, Spyware Doctor (StartUpGuard), PrevX, WinPatrol, ProcessGuard, etc. ?
Well, as a matter of fact I did install ad-awere SE and spy sweeper. And I noticed, probably just after spy sweeper instalation - don’t remember exactly, that the bottom right ‘a’ icon disappeared. I performed uninstall of spy sweeper but still have ad-aware SE. I did also uninstall avast 4.7 and tried to install again, but as I mentioned earlier with no success. After instalation thera is still no ‘a’ icon bottom right corner of desktop and the icon on the desctop does not look as it should. Any suggestions? :-\
I have done uinstaltion of ad-awere SE as well as avast 4.7. Then I have installed avast again but with the same result 
I got no ida what to do >:(
And I am not able to find ashDisp.exe in the location you presented :o
Even after reinstalling avast ashdisp.exe isn’t present, that is the default installation address.
AdAware free is OK it doesn’t have the problem function, AdWatch. SpySweeper has a monitor of start-up programs and should have asked you permission, it should also have created a back-up so you could restore incorrect detections/decisions.
Try a repair of avast. Add Remove programs, select ‘avast! Anti-Virus,’ click the Change/Remove button and scroll down to Repair, click next and follow. You need to be on-line to do this.
Hi! And thanks for your help!!!
Well, I did what you suggested, but the problem is that when I click Change/Remove the only thing that is displayed is installation procedure. I am not able to scroll this button to repair mode I have Windows XP Home edition. :-[ Any other suggestions?
Thanks in advance!!!
Try to download Avast uninstall utility from http://avast.com/eng/avast-uninstall-utility.html .
Then install latest version of Avast again. A ball Avast icon should appear in your system tray. If not make shortcut in your start up folder as advised you DavidR before.
Hi i think you have a root virus since my avast dissapaired the same way. so i tried the f-secure blacklight and panda anti rootkit to remove it.
I also tried to uninstall and install and after reboot it couldnt find the ashdisp.exe
So hope you will be more lucky to solve this problem since im still trying :-[
Hi!
I was removing avast with the tool from avast web site. Othervise it was not possible. Regarding F-Secure: I was trying to install this as well but without luck. Also NAV ???
It looks like I’ll have to foremat my PC. F…!!!
If you are having problems installing other AVs it could well be a rootkit killing them.
See http://forum.avast.com/index.php?topic=26554.0
http://forum.avast.com/index.php?topic=25941.0
http://research.pandasoftware.com/blogs/research/archive/2006/12/14/Rootkit-cleaner.aspx
http://www.f-secure.com/blacklight/try_blacklight.html
What were the problems in trying to install or run these ?
You need to exercise care if you installed NAV this can be very difficult to remove at the best of times and when you clearly have a problem possibly more so.
When you click the Change/Remove you should get a pop-up with other options, see image.
http://img.photobucket.com/albums/v325/for-dwr/avast-repair.jpg
Well, when installing other AV’s simply nothing happened. It looked like none of them were installed. During installation of NAV some kind of error was displayed. In case of s-secure the installation process started but… nothing happpened. Any icon on desktop and when I opened it in Program Files there was no startin icon. In case of the other AV’s the installation procedure didn’t even start at all.
I tried to click Change/Remove but there is no pop-up. Funny, 'cause on my laptop it works . I am pretty sure this must be this f…n rootkit shit. Appology for my words, but it annoys me very much. To say it diplomatic 
when I click change/remove button on my pc the small window with: choose the language appears, than avastAntivirus setup. Nothing more.
You certainly seem to have other operating system problems that are complicating the problem.
Can you boot into safe mode ?
http://www.pchell.com/support/safemode.shtml
If you can try installing the anti-rootkit tools from there.
ALLELUIA!!! VICTORY!!!
Panda did manage it. I men the panda root remover or somthing like that. I checked the links you indicated and simply followed. And it managed. UFFFFFFFFF!!!
Thank you Mr. DavidR for your patience and help. I relly do appreciate it. Maby one day I’ll be able to pay back
Which software can you recommand to install on pc to protect against adaware and spyware??
f…
To early! Strange! The icon on desktop is the ‘a’ icon. After reinstalling avast full scan of discs was performed. I thought it works O.K. now. But… when I clicked this desktop icon still the same problem, still no icon in task bar bottom left and still cannot find .exe :-[
Do you have a firewall ?
One that provides outbound protection and XP’s (if that is what you have) doesn’t provide any. Without a firewall you will be fighting an uphill battle to remain clean.
Did you read these other forums I gave previously as they would appear to have the same problem ?
See http://forum.avast.com/index.php?topic=26554.0 and
http://forum.avast.com/index.php?topic=25941.0 this topic also provides links to on-line scans.
For software, just look at my signature that I would say is a good start point.
It looks like the rootkit is still at large, so you should also install and then run the other anti-rootkit tool.
Now that Panda has done some cleaning it may be worth trying to install BlackLight again. If it still won’t, see if an F-Secure on line scan will help