I know this might seem a bit esoteric, but...
Google Groups allows people to post messages to, and to read messages in, a large number of news groups. Some of these news groups were created by Google users. Others of them are a part of something called Usenet. Usenet pre-dates Google by many years. Anyway, since 2 August, Google has not been showing posts made to Usenet groups since that time. This affects thousands of people all over the world, including me. Google has not acknowledged this problem, and there is no way to communicate with Google to ask them about it. I became so frustrated by this that I phoned their London office. You get a recording which asks you to dial the extension, if you know it. If you don't know it the recording hangs up. So, I started dialling random extensions. After a few tries I got the conference room - and the person there was unhelpful. After a few more tries I managed to start a conversation with somebody and I told him my tale of woe. One of his first questions was "How did you get this number?"
Anyway, he knew nothing about Google Groups. I gave him my email address, in case he finds out anything. And there it lies. Google Groups is still broken.
