This is what happened to me.

A database in MS SQL Server 2005 is being used for a forum software. It's been running flawlessly for years.

In the DB tables, all entries are correct and all messages are there. I can see them.

BUT, for example, when searching for a specific post with a simple query like

SELECT * from pgd_messages where threadId = 10990 (=return all posts belonging to thread 10990)

I only get one record as a result, even though I know and I found other messages being in the threadId 10990 . In other threads I may get more than one results, but not all, and in others I will get all results.
Also, those same messages/entries that are not returned by the query, are not shown in the forum, which is in fact suffering from some "missing message" problem.

What is wrong? I am not an expert in SQL Server, but the problem must not be in the forum software, and more likely be somwhere "between" the table containing all data and some index which is corrupted, and which is used by the SELECT function.

Has this happened to anyone? Any help is greatly appreciated!