User reporting problem with installer

[Thomas]

User downloads and installs three of my applications - they are all sibling tools based on the same script but of course with unique AppID, AppMutex and install paths. 

This is the first report in many years resembling anything like this, but still, I take all reports seriously. User is a developer himself and describes the problem like this:

"Tool1 installed without a problem and seems to be working fine.
When I tried to install the other two, Tool2 and Tool3, both went through this same process:
1. Complained that I needed administrative privileges in order to install. I was logged in as administrator. But then it proceeded to continue on anyway.
2. Again, the installation halted. I'm sorry, I do not remember the error, and cannot now reproduce it, but it again told me It could not install the software and when I selected OK, it proceeded with the installation. I'm going from memory, but I believe that was before the prompt asking me to select a language.
3. The installation went to completion, and when trying to start the application, it will show on screen for 3 to 5 seconds, then disappear. This is the same scenario for both of the programs I mentioned above."

User reports system:

OS Name        Microsoft Windows 7 Ultimate        
Version        6.1.7601 Service Pack 1 Build 7601        
System Type        x64-based PC        

Here are some of my installer script setup:

[Setup]

AllowNoIcons=true

WindowVisible=false

UsePreviousSetupType=true

UsePreviousGroup=true

EnableDirDoesntExistWarning=true

OutputDir=output\

AlwaysShowDirOnReadyPage=true

AlwaysShowGroupOnReadyPage=true

Compression=lzma

DisableStartupPrompt=true

ShowLanguageDialog=yes

PrivilegesRequired=admin

ArchitecturesInstallIn64BitMode=x64

DisableDirPage=false

...

I am unsure if step #3 can or can not be attributed to behavior in my software or installer or system?

I am using InnoSetup 5.6.1 (u)