Open Windows Explorer and at the top, hit the Tools menu, then Folder Options, then the File Types tab. Then scroll down to SWF and see if it's set for the SAflashplayer 6. That's what my problem was. I just set it back to SA flashplayer 8. That's in the flash 8 Players folder. Just reset it and it all works again.
If that doesn't do it, post your html page here, there may be something wrong with your code. Did you use dreamweaver?