Nut upsuser - Aug 2014 - win7 x64 victron driver exiting with error

Operating system Windows 7 x64
NUT version 2.6.5 Windows port
UPS Victron NetPro connected via serial port

When I run driver when UPS cable is connected to computer's serial port it
exits with following output
 victronups  - -DDDD -a victron
Network UPS Tools -GE/IMU/Victron UPS driver 0.20 (2.6.5.-3723:3731M)
0.000000	debug level is "4"
0.000000	w32_serial_open (COM1)
0.000000	setting initial state on COM1
0.015600	0000000050 = w32_serial_open (COM1)
0.015600	Warning: no locking method is available: No error
0.015600	tcgetattr(COM1): Input/output error

But... when I run the driver and few seconds later connect the cable to
serial port it works correctly.
So far no solution found, plz help.