This is not an error message, but something that might be able to be fixed. When someone (as Bev just did, whether on purpose, or inadvertently) leaves the Subject line empty, then the thread cannot be accessed from the New Messages Since Your Last Visit page. In fact, if there are a lot of threads in a person's list, it could be difficult to find. I have noticed nonlinks or missing links before, but my "genius" mind simply did not make the connection until just now!