We do a lot of development here which means we have to support older platforms, unfortunately. Registry.SetValue is not working in Windows 98 and Windows ME, at all (I havent' tested NT, but 2000 & XP are fine). SF 7.0.3.0
%Customer% is a session variable set to: Software\\ABYC_2005_test
Debug.SetTraceMode(true);
Debug.ShowWindow(true);
AcrobatReader="C:\\Program Files\\Adobe\\Acrobat 5.0\\Reader\\AcroRd32.exe";
Registry.SetValue(HKEY_CURRENT_USER, SessionVar.Expand("%Customer%"), "AcrobatExe", AcrobatReader, REG_SZ);
Error=Application.GetLastError();
Debug.Print("Error code output to debug window: "..Error);
result = Registry.GetValue(HKEY_CURRENT_USER, SessionVar.Expand("%Customer%"), "AcrobatExe", true);
Debug.Print("Registry entry: "..result);

