NCR k590 POS printer problem

I am developing application that uses k590 POS printer to print receipts.
I am programming in Delphi under WinXP.

For printing I used simple assign/rewrite/write combination to send pure ESC
sequences to printer, and everything worked OK.
But, when PC is shut down and started again application doesn't print!!!

I concluded it is about 'disabled' COM port and I tryed to open it using
Windows API. I have set up all the parameters etc., but still I can not use
the printer!

Does someone know what else could I do?

When using standard OPOS ocx library for POS printer it works, but I can not
set condensed fonts by sending ESC through OPOS.