Try putting your subtitles into C:\subtitles (or any absolute paths you set up in the VSFilter config), and see if they are loaded then.
I'm suspecting WMP is just clever and hides the filename/path, so VSFilter can have no clue what to look for.
Didn't work
Found another problem to, I know I said otherwise earlier as it seems I jumped to conclusions I thought if the movie had embedded subs it would show them which it didn't for all files. ..... (feels stupid)
WMP11
vsfilter is loading if the movie have embedded subs, though it doesn't load external
vsfilter isn't loading at all if the movie is missing embedded subs (guess as I only have 1 file without embedded)
Will post the log for that file below though it wont help much :/, WMP11 wierdness gah
Media Information of: D:\Filmer\1408.2007.720p.BluRay.DTS.x264-SiNNERS\1408.2007.720p.BluRay.x264-SiNNERS.srt
General:
Filename: 1408.2007.720p.BluRay.x264-SiNNERS.srt
Filesize: 55.8 KiB
Format:
PlayTime:
0 video stream(s), 0 audio stream(s), 0 subtitle stream(s).
File: D:\Filmer\1408.2007.720p.BluRay.DTS.x264-SiNNERS\1408.2007.720p.BluRay.x264-SiNNERS.mkv
Filter 0: Default DirectSound Device
Filename: quartz.dll
Filter CRC: CRC Unavailable.
Date: ERROR: File Not Found.
Filter 1: Video Renderer
Filename: quartz.dll
Filter CRC: CRC Unavailable.
Date: ERROR: File Not Found.
Filter 2: ffdshow Audio Decoder
Filename: C:\Program Files\Combined Community Codec Pack\Filters\FFDShow\ffdshow.ax
Filter CRC: 8DF19053
Date: 2008-09-18 | 00:57:42
Filter 3: DirectVobSub (auto-loading version)
Filename: C:\Program Files\Combined Community Codec Pack\Filters\VSFilter.dll
Filter CRC: B522D064
Date: 2008-09-20 | 18:14:14
Filter 4: CoreAVC Video Decoder
Filename: C:\Program Files\CoreCodec\CoreAVC Professional Edition\CoreAVCDecoder.ax
Filter CRC: 78F2022B
Date: 2008-10-17 | 13:49:14
Filter 5: D:\Filmer\1408.2007.720p.BluRay.DTS.x264-SiNNERS\1408.2007.720p.BluRay.x264-SiNNERS.mkv
Filename: C:\Program Files\Combined Community Codec Pack\Filters\Haali\splitter.ax
Filter CRC: F16EC449
Date: 2008-03-29 | 08:42:30
Media Information of: D:\Filmer\1408.2007.720p.BluRay.DTS.x264-SiNNERS\1408.2007.720p.BluRay.x264-SiNNERS.mkv
General:
Filename: 1408.2007.720p.BluRay.x264-SiNNERS.mkv
Filesize: 6.56 GiB
Format: Matroska
PlayTime: 01:52:26.042
Application: mkvmerge v2.1.0 ('Another Place To Fall') built on Aug 19 2007 13:40:07
Application: libebml v0.7.7 + libmatroska v0.8.1
1 video stream(s), 1 audio stream(s), 0 subtitle stream(s).
Video Stream 0:
Length: 01:52:19.291
Frames: 161743, 23.976 fps,
Codec: V_MPEG4/ISO/AVC (Family: )
Dimensions: 1280x528, AR: 2.35
Audio Stream 0:
Codec: DTS, A_DTS,
Sampling Rate: 48 KHz
Channel(s): 6 channel
CCCP 2008-09-21 Status
Install Dir: C:\Program Files\Combined Community Codec Pack
Filters
CCCP ffdshow installed, location: C:\Program Files\Combined Community Codec Pack\Filters\FFDShow\ffdshow.ax
CCCP CoreWavPack installed, location: C:\Program Files\Combined Community Codec Pack\Filters\WavPackDSDecoder.ax
CCCP Haali Media Splitter installed, location: C:\Program Files\Combined Community Codec Pack\Filters\Haali\splitter.ax
CCCP MPV Decoder installed, location: C:\Program Files\Combined Community Codec Pack\Filters\Mpeg2DecFilter.ax
CCCP VSFilter installed, location: C:\Program Files\Combined Community Codec Pack\Filters\VSFilter.dll
CCCP WMV9VCM NOT Installed but other version found: Registry filepath invalid. Location unknown.
Players
CCCP MPC Installed, location: C:\Program Files\Combined Community Codec Pack\MPC\mplayerc.exe
CCCP ZoomPlayer Installed.
System Information
Operating System: Windows Vista™ Ultimate (6.0, Build 6001) Service Pack 1 (6001.vistasp1_gdr.080917-1612)
Processor: Intel(R) Core(TM)2 Quad CPU Q8200 @ 2.33GHz (4 CPUs), ~2.3GHz
DirectX Version: DirectX 10
Physical RAM: 3582MB
Virtual Memory: 2047MB
Video Information
Video Card: ATI Technologies Inc. ATI Radeon HD 4800 Series
Video Memory: 2554 MB
Chip Type: ATI Radeon Graphics Processor (0x9442)
Driver Filename: atidxx32.dll,atidxx64,atiumdag.dll,atiumdva.cap,atiumd64,atiumd6a,atitmm64
Driver Version: 7.15.0010.0154 | 10/27/2008 20:38:58
Disp Settings: HP w19b/w19e Wide LCD Monitor | 1440 x 900 (32 bit) (60Hz)
Audio Information
Audio Device: Realtek Digital Output (Realtek High Definition Audio)
Driver Name: RTKVHDA.sys
Driver Version: 6.00.0001.5667 | 7/16/2008 11:51:00
Default Sound Playback: true
Default Voice Playback: true
EDIT : mpc-hc works like its intended for that file, external subs vsfilter loading