I am not sure why that is happening for so long
I can only offer the usual stuff.
1. Clear cache/cookies - I see you have done this.
2. Disc clean
3. Defrag
4. Uninstall Shockwave/Flash Player (reboot computer to get rid of any leftover Shockwave) and re-install. - Did you reboot inbetween?
5. Have all computer updates
6. Clear your Shockwave Cache? Disclaimer: I have done this several times over the years but please read the instructions on the webpages yourself. I tend to do the first way but believe either way will do it.
http://www.wikihow.com/Delete-Flash-Cookies
https://forums.adobe.com/thread/977699
7. Make sure your Firewall and any anti-malware/virus has the IP allowed. My Malwarebyte Anti-Malware used to block it until I put it on its inclusion list.
8. If you use wi-fi normally have you tried using a cable to make sure it's not your wi-fi dropping out?
If it starts working then please let us know which ones you have done so it can potentially help others with the same problem. Good luck!