I encountered this recently and had to switch to Chrome to use Live Chess since it was unusable otherwise. Could be to do with a couple of extensions I'd installed (mainly blocking javascripts and cross-application tracking activity).

Well, I'm guessing you've tried Chrome, right? It's lightning fast on live chess for me.

http://blog.chess.com/NimzoRoy/diagnosing-and-fixing-internet-problems

You're having problems with all browsers? Have you tried rebooting your router and modem? Checked all cables to make sure they're tight? And rebooted the PC when a problem shows up?

Sounds like the problems are at your end, can you log onto chess.com using another PC preferably one using your OS and see what happens?

The cables are not a laughing matter when they're loose, because the device may still work - half-assed that is. And after my cable company gave me a new modem I hooked it up with a USB cable they provided, but the repairman told me the other cable they provided (ethernet cable i believe) is way better, and it is. So don't blow this issue off in the future. AND once in a blue moon the cable itself is shot and needs to be replaced.

I think you should just use Chrome for chess.com and get over it, but if you love troubleshooting PCs I guess it's OK. After awhile I get sick and GD tired of having to fix the PC instead of just using it, but maybe that's just me; well at least I know enuff to have only had to pay someone else to fix my PC twice in the last 20 yrs or so.