Hello everybody, this is my first message here. Today I had a problem converting a Long (Int64) to an Integer (Int32). The problem is that my code was always working in 32-bit environments, but when I try THE SAME executable in a 64-bit computer it crashes with a System.OverflowException exception. I've prepared this test code in VS2008 in a new project with default settings: Module Module1 Sub Main() Dim alpha As Long = -1 Dim delta As Integer Try delta = CInt(alpha And UInteger.MaxValue) Console.WriteLine("CINT OK") delta = Convert.ToInt32(alpha And UInteger.MaxValue) Console.WriteLine("Convert.ToInt32 OK") Catch ex As Exception Console.WriteLine(ex.GetType().ToString()) Finally Console.ReadLine() End Try End Sub End Module On my 32-bit setups (Windows XP SP3 32-bit and Windows 7 32-bit) it prints "CINT OK", but in the 64-bit computer (Windows 7 64-bit) that I've tested THE SAME executable it prints the exception name only. Is this behavior documented? I tried to find a reference but failed miserably. For reference I leave the MSIL code too: .method public static void Main() cil managed { .entrypoint .custom instance void [mscorlib]System.STAThreadAttribute::.ctor() = ( 01 00 00 00 ) // Code size 88 (0x58) .maxstack 2 .locals init ([0] int64 alpha, [1] int32 delta, [2] class [mscorlib]System.Exception ex) IL_0000: nop IL_0001: ldc.i4.m1 IL_0002: conv.i8 IL_0003: stloc.0 IL_0004: nop .try { .try { IL_0005: ldloc.0 IL_0006: ldc.i4.m1 IL_0007: conv.u8 IL_0008: and IL_0009: conv.ovf.i4 IL_000a: stloc.1 IL_000b: ldstr "CINT OK" IL_0010: call void [mscorlib]System.Console::WriteLine(string) IL_0015: nop IL_0016: ldloc.0 IL_0017: ldc.i4.m1 IL_0018: conv.u8 IL_0019: and IL_001a: call int32 [mscorlib]System.Convert::ToInt32(int64) IL_001f: stloc.1 IL_0020: ldstr "Convert.ToInt32 OK" IL_0025: call void [mscorlib]System.Console::WriteLine(string) IL_002a: nop IL_002b: leave.s IL_0055 } // end .try catch [mscorlib]System.Exception { IL_002d: dup IL_002e: call void [Microsoft.VisualBasic]Microsoft.VisualBasic.CompilerServices.ProjectData::SetProjectError(class [mscorlib]System.Exception) IL_0033: stloc.2 IL_0034: nop IL_0035: ldloc.2 IL_0036: callvirt instance class [mscorlib]System.Type [mscorlib]System.Exception::GetType() IL_003b: callvirt instance string [mscorlib]System.Type::ToString() IL_0040: call void [mscorlib]System.Console::WriteLine(string) IL_0045: nop IL_0046: call void [Microsoft.VisualBasic]Microsoft.VisualBasic.CompilerServices.ProjectData::ClearProjectError() IL_004b: leave.s IL_0055 } // end handler } // end .try finally { IL_004d: nop IL_004e: call string [mscorlib]System.Console::ReadLine() IL_0053: pop IL_0054: endfinally } // end handler IL_0055: nop IL_0056: nop IL_0057: ret } // end of method Module1::Main I suspect that the instruction that is behaving differently is either conv.ovf.i4 or the ldc.i4.m1/conv.u8 pair. If you know what is going on here please let me know Thanks