You might want to check the audio stream within the wmv, as not all audio formats are supported.
Alot of video playback problems on the PS3 are becuase of the audio stream.
This might help:
Media
1. External drive
* Only FAT32 [FW 2.50]
* Any size (Windows doesn't allow for FAT32 disks > 32GB. Use any Linux utility instead) [FW 2.50]
* Chose Triangle/"Display Files" to see anything not inside VIDEO folder [FW 2.50]
* Only files contained in VIDEO folder will display directly [FW 2.50]
* Files may not be bigger than 4GB (limitation of FAT32) [FW 2.50]
2. HTTP (via webbrowser and HTTP server)
* Only files < 4GB [FW 2.40]
* Tools: Apache Web Server
3. DLNA
* Any file size [FW 2.50]
* Allows for live transcoding [FW 2.50]
* Tools: TVersity
4. AVCHD formated external media
* No copying of files possible [FW 2.50]
* Allows for additional codec combinations, most notably VC-1 in M2TS [FW 2.50]
* Tools: TSMuxer
Containers
1. M2TS
* Allowed video codecs
o h.264 (MPEG-4 AVC) [FW 2.50]
o VC-1 on AVCHD formated disks [FW 2.50]
* Allowed audio codecs
o AC3 (Dolby Digital) [FW 2.50]
* Multiple audio streams
o yes [FW 2.50]
* Tools: TSMuxer
2. MP4
* Allowed video codecs
o h.264 (MPEG-4 AVC) [FW 2.50]
* Allowed audio codecs
o AAC (MPEG 4 Audio) [FW 2.50]
* Tools: MP4Box, YAMB
3. WMV
* Allowed video codecs
o VC-1 [FW 2.50]
* Allowed audio codecs
o WMA (not pro, only stereo) [FW 2.50]
* Tools: SolveigMM ASF Muxer, GraphEdit
4. AVI
* Allowed video codecs
o DivX [FW 2.50]
* Allowed audio codecs
o MP3 [FW 2.50]
* Tools: VirtualDub, MEncoder
Video Codecs
1. h.264 (MPEG-4 AVC)
* Maximum resolution
o >=1920x1080 [FW 2.50]
* Interlaced
o Optional [FW 2.50]
* Non-square aspect ratio
o Unknown
* Maximum framerate
o >= 60 fps [FW 2.50]
* Highest allowed profile
o 4.1 [FW 2.50]
* Tools: MEncoder
o Mencoder.exe -nosound -noskip -mc 0 -of rawvideo -ovc x264 -x264encopts bitrate=8000:threads=2:frameref=2:bframes=2:debloc k:level=41:direct_pred=auto

artitions=p8x8,b8x8:m e=hex:me_range=16:subq=5:chroma_me:mixed_refs:bime :trellis=1:weight_b:b_pyramid:nr=0 -ofps 24000/1001 -vf harddup -v -noautosub -sid 8190 INPUT -o OUTPUT.h264
o Adjust (video bitrate) bitrate=8000, (output framerate) ofps 24000/1001, (input file) INPUT, (output file) OUTPUT.h264 and (subtitle id) sid 8190 accordingly
2. VC-1
* Maximum resolution
o >=1920x1080 [FW 2.50]
* Interlaced
o Optional
* Non-square aspect ratio
o Unknown
* Maximum framerate
o >= 30 fps [FW 2.50]
* Highest allowed profile
o ???
3. DivX
* Maximum resolution
o ???
* Interlaced
o ???
* Non-square aspect ratio
o ???
* Maximum framerate
o ???
* Highest allowed profile
o ???
3. MPEG-1 Video
* Maximum resolution
o ???
* Interlaced
o ???
* Non-square aspect ratio
o ???
* Maximum framerate
o ???
* Highest allowed profile
o ???
4. MPEG-2 Video
* Maximum resolution
o ???
* Interlaced
o ???
* Non-square aspect ratio
o ???
* Maximum framerate
o ???
* Highest allowed profile
o ???
Audio Codecs
1. AC3 (Dolby Digital)
* Maximum Sample Rate
o >=48khz [FW 2.50]
* Channels
o >=5.1 [FW 2.50]
* Tools: eac3to
o eac3to input output.ac3 -448
2. AAC (MPEG-4 Audio)
* Maximum Sample Rate
o >=48khz [FW 2.50]
* Channels
o >=5.1 [FW 2.50]
* Tools: Nero AAC encoder, FAAD
3. MP3
* Maximum Sample Rate
o >=48khz [FW 2.40]
* Channels
o >=2 [FW 2.50]
* Tools: LAME