Thanks for asking! The 64-bit Windows 7 operating system is supported as long as you are using a 32-bit web browser. I would recommend uninstalling the SlingPlayer plug-in from your computer and reinstalling it. I also would recommend clearing the cache and cookies from your intenet options, this could help free your computer and improve the performance.
Here is a few articles to help uninstalll the plugin, and an article that lists the supported browser plug-in:
If you have any other questions, feel free to respond or give us a call at 1-877-467-5464. We are open seven days a week, from 10:00am to 10:00pm EST.
Hope this helps,
The Sling Media Moderation Team