I don't have NT 3.51 to test, but try this:

Go to Control Panel, choose ports. I believe you can set the address ranges for each port there. It seems that you have now overlapping zones for both LPTs.

Vlad

>In Windows NT 3.51 I am having trouble with an EZ135 parallel port drive attached to LPT1 (I/O address 378) interfering with a printer on LPT2 (I/O address 278). When the EZ135 PP drive is not connected the printer on LPT2 works just fine.
>
>In Event Viewer I get the following error messages and event details:
>
>Source: Parport, EventID: 22
>
>Details:
>A conflict has been detected between two drivers which claimed two overlapping Io port regions. Driver Parport, with device <\Device\ParallelPort0.Translated>, claimed an IO port range with starting address in data address 0x28 and 0x2c, and length in data address 0x30.
>
>Source: Parport, EventID: 22
>
>Details:
>A conflict has been detected between two drivers which claimed two overlapping Io port regions. Driver epathdx, with device <\Device\ScsiPort1.Translated>, claimed an IO port range with starting address in data address 0x28 and 0x2c, and length in data address 0x30.
>
>Source: Parport, EventID: 5
>
>Details:
>The hardware addresses for are already in use by another device.
>
>Source: Parport, EventID: 21
>
>Details:
>Unable to get device object pointer for port object.
>
>My system is a 486 DX4 100 Mhz, (AMI BIOS, Not PNP and ports are not configurable from the BIOS), with 40 Mb RAM, two ECP parallel ports.
>
>
>David Kolb