Google Groups search is only returning one page of results for me at the moment – there's no way to navigate past the first page. I understand Groups is a relatively little-used and neglected Google property, but this is kind of strange.

Here is a search of groups for [example].
groups.google.com/groups/search?q=example&start=0
http://groups.google.com/groups/search?q=example&start=0

There are no navigation links, but you can either use a bookmarklet to navigate or manually set the value of "start" in the url.

Here are the next ten results.
groups.google.com/groups/search?q=example&start=10
http://groups.google.com/groups/search?q=example&start=10

Jesse's bookmarklet site has bookmarklets to increment or decrement a url by one.
http://www.squarefree.com/bookmarklets/misc.html#increment
The "start" value should be last number in the url. By setting "num=1", you could navigate the results one at a time.
groups.google.com/groups/search?q=example&num=1&start=0
http://groups.google.com/groups/search?q=example&num=1&start=0

To get to the next page of ten results you can modify the bookmarklet to increment by ten. I would post the modified bookmarklet itself, but I suspect this forum would corrupt it. Try changing "IB=1;" to "IB=10;". The bookmarklet uses javascript that must be enabled. Do not set "num=1" if you use this.

You may also want to look at one hundred results per page. This can be specified on the advanced page.
http://groups.google.com/groups/advanced_search
Here are one hundred groups results for [example].
groups.google.com/groups/search?q=example&num=100&start=0
http://groups.google.com/groups/search?q=example&num=100&start=0