I think there are updates coming for SR3 for the addons. But you should check with Smith Micro to see iof they know the problem with SR3 and PZ files

I use windows 7 as well. The search engine in Poser uses the internal windows 7 search engine to search locally. If you do the same query in Windows Search - do you get results (this is to check of the index is still ok)

In the test I just did, I search for "bag" in all categories and got back a few 100 results across 6 runtimes, so the search does not seem to be broken as such.
They made a few changes to speed up local search and to have a full search over all categories if none are checked.  Are you certain that the search did finish? (look at the search button)