Why oh why will this not work!!!

My brother and I are both installing mythtv on separate systems. We're using kubuntu dapper as the base system, with pvr-150 capture cards. The only difference between our system is the mother board: I'm using an asus a8n5x, he's tried a foxcom winfast k7s, and an eg k7s5a.

I have no problems at all with the pvr-150's IR interface. On my brother's systems however, the IR hardware is never found. All other ivtv funtions work fine for him, it's just the IR that's not being detected.

We have swapped PVR-150s and the problem stays with my brother's system, so it's not a hardware problem with the capture card. I put his hard drive into my system, booted it, and the IR works fine, so there is no problem with the software install.

No matter what we've tried we can't seem to get the drivers to find he hardware on his system.

kernel: 2.6.15-27-386
ivtv 0.4.6 and 0.4.7 (tried both)
lirc 0.8.0

module options:
alias char-major-61 lirc_i2c
alias char-major-81-0 ivtv
alias char-major-81-1 ivtv
options ivtv tuner=50
options lirc_dev debug=1
options lirc_i2c debug=1

dmesg output from failing system:
[17179587.092000] Linux video capture interface: v1.00
[17179587.604000] ivtv:  ==================== START INIT IVTV ====================
[17179587.604000] ivtv:  version 0.4.7 (tagged release) loading
[17179587.604000] ivtv:  Linux version: 2.6.15-27-386 preempt 486 gcc-4.0
[17179587.604000] ivtv:  In case of problems please include the debug info between
[17179587.604000] ivtv:  the START INIT IVTV and END INIT IVTV lines, along with
[17179587.604000] ivtv:  any module options, when mailing the ivtv-users mailinglist.
[17179587.780000] ivtv0: Autodetected WinTV PVR 150 card (cx23416 based)
[17179587.780000] ivtv0: Unreasonably low latency timer, setting to 64 (was 32)
[17179587.800000] ivtv0: i2c attach to card #0 ok [client=tveeprom, addr=50]
[17179587.832000] tveeprom 0-0050: Hauppauge model 26132, rev F0B2, serial# 9398558
[17179587.832000] tveeprom 0-0050: tuner model is TCL M2523_5N_E (idx 112, type 4)
[17179587.832000] tveeprom 0-0050: TV standards NTSC(M) (eeprom 0x08)
[17179587.832000] tveeprom 0-0050: audio processor is CX25841 (idx 35)
[17179587.832000] tveeprom 0-0050: decoder processor is CX25841 (idx 28)
[17179587.832000] tveeprom 0-0050: has no radio, has IR remote
[17179587.888000] tuner 0-0061: chip found @ 0xc2 (ivtv i2c driver #0)
[17179587.888000] ivtv0: i2c attach to card #0 ok [client=(tuner unset), addr=61]
[17179588.036000] cx25840 0-0044: ivtv driver
[17179588.036000] cx25840 0-0044: cx25841-23 found @ 0x88 (ivtv i2c driver #0)
[17179590.936000] cx25840 0-0044: loaded v4l-cx25840.fw firmware (14264 bytes)
[17179590.992000] ivtv0: i2c attach to card #0 ok [client=cx25840, addr=44]
[17179591.032000] wm8775 0-001b: chip found @ 0x36 (ivtv i2c driver #0)
[17179591.040000] ivtv0: i2c attach to card #0 ok [client=wm8775, addr=1b]
[17179591.768000] ivtv0: loaded v4l-cx2341x-enc.fw firmware (262144 bytes)
[17179591.984000] ivtv0: Encoder revision: 0x02050032
[17179591.984000] ivtv0: Allocate DMA encoder MPEG stream: 128 x 32768 buffers (4096KB total)
[17179591.984000] ivtv0: Allocate DMA encoder YUV stream: 194 x 10800 buffers (2048KB total)
[17179591.984000] ivtv0: Allocate DMA encoder VBI stream: 120 x 17472 buffers (2048KB total)
[17179591.984000] ivtv0: Allocate DMA encoder PCM audio stream: 455 x 4608 buffers (2048KB total)
[17179591.984000] tuner 0-0061: type set to 50 (TCL 2002N)
[17179592.060000] ivtv0: Initialized WinTV PVR 150, card #0
[17179592.060000] ivtv:  ====================  END INIT IVTV  ====================
[17179593.040000] lirc_dev: IR Remote Control driver registered, at major 61
[17179593.048000] lirc_i2c: no version for "lirc_unregister_plugin" found: kernel tainted.
[17179593.100000] bttv: driver version 0.9.16 loaded
[17179593.100000] bttv: using 8 buffers with 2080k (520 pages) each for capture
[17179593.196000] cx2388x v4l2 driver version 0.0.5 loaded
[17179593.208000] lirc_i2c: probe 0x1a @ ivtv i2c driver #0: no
[17179593.216000] lirc_i2c: probe 0x18 @ ivtv i2c driver #0: no
[17179593.228000] lirc_i2c: probe 0x71 @ ivtv i2c driver #0: no
[17179593.236000] lirc_i2c: probe 0x4b @ ivtv i2c driver #0: no
[17179593.244000] lirc_i2c: probe 0x64 @ ivtv i2c driver #0: no
[17179593.256000] lirc_i2c: probe 0x30 @ ivtv i2c driver #0: no
[17179593.264000] lirc_i2c: probe 0x6b @ ivtv i2c driver #0: no
[17179593.296000] i2c-sis96x version 1.0.0
[17179593.296000] sis96x_smbus 0000:00:02.1: SiS96x SMBus base address: 0x10c0

Both boards that he tried have irda onboard, which we disabled (one board didn't have the optional hardware installed on it, just the bios). Mine doesn't have irda. Is it possible that the onboard irda is getting in the way?

He doesn't want to keep buying different motherboards until he happens to get one that works, we'd rather get to the bottom of this.

Can anyone suggest any more debugging we can do?