OK...from one of your posts, it seemed like there might have been a possibility that it was a different file type. Anyway, the only way to play wmv content, now a days, is with Flip4Mac...however, there is still chance a wmv file will not play, due to the processing that was used when it was created. Some content providers deviate from normal and use different, unsupported codecs underneath the wmv wrapper. The Flip4Mac people do a pretty good job of keeping up with all those new codecs, and release compatibility updates regularly, but there are, obviously, a few out there that don't fit in.
The bottom line is...maybe you've got one of those rogue wmv's. Did you get it off a web site? If so, post a link and I can see if it plays here....or upload it to a server and point to it.