No SERP Results Beyond Page 1 in Google: Test or Bug?

Update: "This is a bug affecting a small number of users. We will work to resolve it as soon as we can," a Google spokesperson tells Search Engine Roundtable.

Reports are surfacing all around the web that Google is only showing the Top 10 results for some users. This means some people can't see links to any further SERPs (i.e., they can't click on to Page 2, 3, 4, etc.) at the bottom of the screen when searching from the Google.com site. Some SEOs are also reporting traffic hits.

Speculation at the moment is that it's either a bug on Google's end or some sort of feature they're testing out, as some users are reporting seeing a second search box.

It has happened with long tail, head tails, signed into Google or signed out.

Anybody else seeing this issue or seen/have any screen shots of this problem?

There are ongoing discussions at Webmaster World and Google Web Search Help.

If you're having this problem, one solution that's worked is to go to image search and then back to web search and Gooooogle will appear as normal.