Sorry that I can't offer a solution - I am posting as I have a similar problem. When I try to connect to the Playstation Network using my PS3, after it whirs away for a while, I get the message

"An error has occurred. You have been signed out of the PLAYSTATION@Network (80710823)"

Note that the error code changes when I try to use the Playstation Store, but the text of the error message is the same. Is there anywhere that I can find out what the error code means? The error message is not all that useful.

I do not have any problems browsing the web apart, interestingly, from Playstation websites e.g. http://eu.playstation.com/ps3.

I have tried a few obvious things to try to determine if there is a problem caused by my router (a Belkin Wireless G Router) like disabling the firewall and/or moving my PS3 into the DMZ but to no avail.

Any ideas?