Can you give us at least one of the website addresses? If you have Flash installed, it should work. Maybe you should uninstall and reinstall.
Error 503 Service Unavailable
Service Unavailable
Guru Meditation:
XID: 964832657
Varnish cache server
For example, it works on youtube, but it doesn't work on like, neopets.
Also, when I try to upload a picture to tinypic, it shows this:
Code:Error 503 Service Unavailable Service Unavailable Guru Meditation: XID: 964832657 Varnish cache server
I've already tried clearing cache, it didn't make a difference.
Maybe they're linked in a way?
EDIT: Just tried uninstalling and reinstalling, didn't fix it.
That looks like a server-generated error at their end. If a site is unresponsive and throws up errors because of a reason like that, you can't do anything about it by changing any settings on your Mac.
The error is only on my mac, my cousin's mac works without any problems. Could it have anything to do with the Mavericks OS?
I wonder if it's your router if that's the case. Not being able to connect to a server could be an error at network level.
That might be the problem. Is there any way to fix this without having to buy a new router?
I think what he meant was a DNS error or a problem with your ISP, not the router's hardware.
What are your DNS settings? Are you using your ISP's DNS or a third party like OpenDNS or Google?
I'm using 8.8.8.8 which I'm guessing is google's DNS.
Just for s's & giggles, try resetting your router to all default settings and see what happens.