I use Firefox as well, but it works for me. If you keep having trouble, you might look into the Real Alternative player, which is what I'm using. It plays RealPlayer files without the bulkiness of the real deal. Uninstall Real Player and try installing Real Alternative would be my first piece of advice.
"You just had a glue OD, and those are pretty regular in my life. So here's another lesson: don't huff too much glue, or your night sucks."