Solved
It seems that, in this case, the name of palleteset must be the same as the command that displays palette
Olde Code
_ps = New Autodesk.AutoCAD.Windows.PaletteSet("Navegador Web", New Guid(PSGGUID))
New Code
_ps = New Autodesk.AutoCAD.Windows.PaletteSet("WEBBWR", New Guid(PSGGUID))
<Autodesk.AutoCAD.Runtime.CommandMethod("HNGRWEBBWR", "WEBBWR", CommandFlags.Transparent)> _
Public Shared Sub ShowWebBrowserPalette()
_ps.Visible = True
End Sub
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