Had a nightmare trying to set this game up on PC, and decided to post a fix for anyone else attempting to play this on a single monitor. Modern DxWnd results in a constant window minimizing issue.

You need DxWnd version 2.04.41. It should work off the bat as other versions will just boot to crash. Choose whichever internal resolution you like in Bloodrayne 2's launcher. Set DxWnd resolution to the same and enjoy.