IIS 4.0 and files in use…

I have a web page which when loaded plays a .wav file on the client computer using the embed or bgsound options. This .wav file needs to be updated periodically. It is kinda like an announcement center. The problem is when this file is playing over the internet, it cannot be overwritten, says the file is in use. I thought everything was cached when read by the client. I need to be able to provide this capability. Can any one help me.

Thanks