GTX1060/Thinkpad X230 - Black screen when external display at boot  

Hello. I have Lenovo Thinkpad X230 with MSI Aero GTX 1060 3GB connected by ExpressCard. My monitor is pretty old and it uses VGA (D-SUB), while this GTX 1060 has only digital output such as HDMI, so i bought an adapter (HDMI to VGA). When I'll start laptop without external display, it works fine so after this i can just plug external diplay to this. But when i have plugged in external display while computer is starting, then bios message freezes and i must restart computer. I have latest graphic drivers. I have 2x4GB 1600MHz Samsung memory and i5-3320M. This is really annoying that i have to connect monitor every time i start computer. Thanks in advance.