Flash Video Stops Buffering and Never Continues

I recently have been experiencing trouble watching a full Flash video from a variety or sources.  The video will buffer about 30sec to 3minutes of data and stop.  The video plays perfectly up to the point where the buffering stopped, but will not continue.  If I try to refresh the browser page, the video no longer loads, I just get the scrolling wheel in the center of the video screen. 

This happens on Firefox v3.6.13 (32-bit), IE v8.0.7600.16385 (32-bit I think) & Chrome v8.0.552.224.  I am using Flash version 10,1,102,64 for Firefox and IE, and Flash v10,1,103,20 for Chrome.

My Operating Systems is Windows 7 64-bit.  I have tried uninstalling Flash and reinstalling it several times.  I have disabled Hardware Accelleration and turned off AVG from any web protection.  I have cleared my cache files and said several prayers!   Every once in a while a video will fully buffer and play, but I cannot figure out a pattern to it.  Most of the videos I watch are either YouTube or Photography tutorials on sites like Photoshopuser.com, planetphotoshop.com or Vimeo.

I've done lots of searching and haven't really found anyone else with this exact issue, but similar ones.  I've tried everything I can think of and am pretty much at my wits end right now.  I'm not a technical novice but this one has me stumped.  Any assistance that can be provided is appreciated.

Thanks,

dave