Getting "You must enter a name" and "Cannot focus a disabled or invisible window" on some machines with hidden UserInfoPage Inno Setup page - inno-setup

Question

I have made a quick installer and in some PC I have found problems when installing. I have "serial number" system and when I press "Next" it gives me an error
You must enter a name
and then:
Cannot focus a disabled or invisible window
But in many other PCs with same SO this works normal. This is the code that I am using:
[Setup]
WizardStyle=modern
UserInfoPage=yes
[Code]
procedure CurPageChanged(CurPageID: Integer);
begin
if CurPageID = wpUserInfo then begin
WizardForm.UserInfoOrgLabel.Hide();
WizardForm.UserInfoOrgEdit.Hide();
WizardForm.UserInfoNameLabel.Hide();
WizardForm.UserInfoNameEdit.Hide();
end;
end;
// Presence of the CheckSerial event function displays the serial number box.
// But here we accept any non-empty serial.
// We will validate it only in the NextButtonClick,
// as the online validation can take long.
function CheckSerial(Serial: String): Boolean;
begin
Result := (Serial <> '');
end;
function NextButtonClick(CurPageID: Integer): Boolean;
var
WinHttpReq: Variant;
Url: string;
begin
Result := True;
if CurPageID = wpUserInfo then
begin
WinHttpReq := CreateOleObject('WinHttp.WinHttpRequest.5.1');
Url := 'Link that i use to check the serial number' +
WizardForm.UserInfoSerialEdit.Text;
WinHttpReq.Open('GET', Url, False);
WinHttpReq.Send('');
// Depending on implementation of the server,
// use either HTTP status code (.Status)
// or contents of returned "page" (.ResponseText)
// Here we use the HTTP status code:
// 200 = serial is valid, anything else = serial is invalid,
// and when invalid, we display .ResponseText
Result := (WinHttpReq.Status = 200);
if not Result then
MsgBox(WinHttpReq.ResponseText, mbError, MB_OK);
end;
end;

Answer 1

With UserInfoPage enabled, filling in the "User name" box is mandatory. The box is pre-filled with a value of RegisteredOwner registry value. If that value happens to be empty, and consequently the box, you cannot leave the page, until you fill it in manually. You get the "You must enter a name" error and Inno Setup moves the focus to the box. That fails with "Cannot focus a disabled or invisible window", as you have the box hidden.
If you do not care about the username, just fill in some dummy value:
WizardForm.UserInfoNameEdit.Text := 'foo';