I am also getting this error when I go online on my PS3. I would sign in, play for about 15 minutes and then the error will hit and sign me out. I can sign in back instantly but it'll do the same thing over again.
I have also accepted the terms and conditions that popped up a couple of days ago when I was signing in on my PS3 and played normally afterwards so I don't know why it hits me with this error now. I heard signing in here or www.sonyentertainmentnetwork.com will give me an option to re-accept the terms and conditions but it never appeared.
Anyone have any other suggestions I could do? Or will Sony release a small patch to fix this?
I followed the link and accepted the terms of the agreement and also changed my password and this resolved the issue for me. (I do not think the resetting of the password is required...just forgot mine.
Best of luck,