A friend of mine suddenly couldn’t access the iTunes Store after upgrading to the latest version, every time he tried to purchase something he kept getting the following error:
“We could not complete your iTunes store request,an unknown error occurred (-9808)”
I couldn’t find anything online about it, so here’s how we fixed it under Windows XP. Go to Start -> Control Panel -> Internet Options -> Advanced Tab, make sure that both the SSL 3.0 and TLS 1.0 options are checked. Then under Security make sure that the “Check for server certificate revocation (requires restart)” is unchecked. Then click ok, restart and fire up iTunes.