MKV file won't play in MediaPortal

[wlgspotter]

TV-Server Version:
MediaPortal Version: 0.2.3.0 RC1 SVN 15080
MediaPortal Skin: Dragon
Windows Version: XP SP2
CPU Type: AMD X2 4600+
HDD: Seagate 320GB + Seagate 400GB
Memory: 1GB DDR2 667MHz CL5
Motherboard: Shuttle SN27P2 System
Motherboard Chipset:
Motherboard Bios:
Video Card: Gigabyte GV-NX73G128D-RH (nVidia 7300GS)
Video Card Driver: 9.1.3.1
Sound Card: OnBoard/ALC882
Sound Card AC3: 1x coax out, 1x optical out
Sound Card Driver: 5.10.0.5202
1. TV Card: Hauppage MCE 150-lp
1. TV Card Type: Analog
1. TV Card Driver: GV-NX73G128D-RH
2. TV Card:
2. TV Card Type:
2. TV Card Driver:
3. TV Card:
3. TV Card Type:
3. TV Card Driver:
4. TV Card:
4. TV Card Type:
4. TV Card Driver:
MPEG2 Video Codec:
MPEG2 Audio Codec:
Satelite/CableTV Provider: Sky TV (NZ)
HTPC Case: Shuttle SN27P2
Cooling:
Power Supply:
Remote: MS MCE Remote
TV: Sony 43" Rear Projection (SDTV)
TV - HTPC Connection: S-Video

Hi:

I'm trying to play an MKV file (non HD/x264 - it uses Xvid for video and Vorbis for audio) of a Japanese anime, however, the file won't play in MP - nothing happens when I select it. I've got ffdshow (might be an old version tho - 2004-10-12-sse2) & Haali Media Splitter installed. FYI, the file played fine under WMP11.

Any ideas/help would be appreciated.

Cheers!