Cannot install Avast...virus?

I’ve been trying to install Avast on a friend’s computer and have been unable to do so. It is the free version(5.1.864.0) and the system is running Windows Vista.

I was trying to get rid of a virus which I believe I was able to do with Malware Byte’s. I’ve since removed it and also run the Norton and McAfee removal tools just in case that was the problem (I have no idea what programs he’s used in the past).

Thanks in advance for any help you can provide.

Below is the part in the installation log where things seem to go wrong:

package: extracted file C:\Program Files\Alwil Software\Avast5\defs\10123101\aswRawFS.dll
13.01.2011 18:25:27 package: vps: going to extract C:\Program Files\Alwil Software\Avast5\defs\10123101\aswScan.dll (4)
13.01.2011 18:25:27 package: extracted file C:\Program Files\Alwil Software\Avast5\defs\10123101\aswScan.dll
13.01.2011 18:25:27 package: vps: going to extract C:\Program Files\Alwil Software\Avast5\defs\10123101\exts.dll (4)
13.01.2011 18:25:27 package: extracted file C:\Program Files\Alwil Software\Avast5\defs\10123101\exts.dll
13.01.2011 18:25:27 package: vps: going to extract C:\Program Files\Alwil Software\Avast5\defs\10123101\fwAux.dll (4)
13.01.2011 18:25:27 package: extracted file C:\Program Files\Alwil Software\Avast5\defs\10123101\fwAux.dll
13.01.2011 18:25:27 package: vps: going to extract C:\Program Files\Alwil Software\Avast5\defs\10123101\list_d.txt (2)
13.01.2011 18:25:27 package: extracted file C:\Program Files\Alwil Software\Avast5\defs\10123101\list_d.txt
13.01.2011 18:25:27 package: vps: ExtractFilesFromPackage(vps_win32-3ae.vpx) returned 0x00000000
13.01.2011 18:25:27 package: vps: Couldn't load C:\Program Files\Alwil Software\Avast5\defs\10123101\aswScan.dll, error 0x000036B1
13.01.2011 18:25:44 system: Uninstalling aswTdi.sys
13.01.2011 18:25:44 system: Stopping service aswTdi
13.01.2011 18:25:44 system: OpenSCManager
13.01.2011 18:25:44 system: OpenService
13.01.2011 18:25:44 system: OpenService, errcode: 0x00000424
13.01.2011 18:25:44 system: Service aswTdi stopped, errcode: 0x00000424
13.01.2011 18:25:44 registry: Deleted registry: Software\Alwil Software\Avast\5.0
13.01.2011 18:25:44 registry: Cannot open reg. key:Software\Microsoft\Windows\CurrentVersion\App Paths\AvastUI.exe
13.01.2011 18:25:44 registry: RegLoadKey(HKEY_USERS, Av_S-1-5-18, C:\Windows\system32\config\systemprofile\NtUser.dat)
13.01.2011 18:25:44 registry: RegLoadKey(HKEY_USERS, Av_S-1-5-19, C:\Windows\ServiceProfiles\LocalService\NtUser.dat)
13.01.2011 18:25:44 registry: Load registry hive ERROR_SHARING_VIOLATION
13.01.2011 18:25:44 registry: RegLoadKey(HKEY_USERS, Av_S-1-5-20, C:\Windows\ServiceProfiles\NetworkService\NtUser.dat)
13.01.2011 18:25:44 registry: Load registry hive ERROR_SHARING_VIOLATION
13.01.2011 18:25:44 registry: RegLoadKey(HKEY_USERS, Av_S-1-5-21-4241358610-77463683-3924183635-1000, C:\Users\Brian\NtUser.dat)
13.01.2011 18:25:44 registry: Load registry hive ERROR_SHARING_VIOLATION
13.01.2011 18:25:44 registry: RegLoadKey(HKEY_USERS, Av_S-1-5-21-4241358610-77463683-3924183635-1003, C:\Users\Tara\NtUser.dat)
13.01.2011 18:25:45 registry: RegUnloadKey
13.01.2011 18:25:45 registry: RegLoadKey(HKEY_USERS, Av_S-1-5-21-4241358610-77463683-3924183635-1004, C:\Users\Jake\NtUser.dat)
13.01.2011 18:25:45 registry: RegUnloadKey
13.01.2011 18:25:45 file: Removing file: C:\Program Files\Alwil Software\Avast5\Aavm4h.dll
13.01.2011 18:25:45 file: Direct delete of file: C:\Program Files\Alwil Software\Avast5\Aavm4h.dll
13.01.2011 18:25:45 file: Removing file: C:\Program Files\Alwil Software\Avast5\AavmRpch.dll
13.01.2011 18:25:45 file: Direct delete of file: C:\Program Files\Alwil Software\Avast5\AavmRpch.dll
13.01.2011 18:25:45 file: Removing file: C:\Program Files\Alwil Software\Avast5\ashBase.dll
13.01.2011 18:25:45 file: Direct delete of file: C:\Program Files\Alwil Software\Avast5\ashBase.dll
13.01.2011 18:25:45 file: Removing file: C:\Program Files\Alwil Software\Avast5\ashServ.dll

A new official version was released today…
Maybe that can works?
http://forum.avast.com/index.php?topic=69305.0

And some questions:
Did you already ran a scan with MBAM?
There are other AV’s before the attempt to install avast! ?
If the answer to question above is positive; did you remove them in the right way?