Windows 2003 SP2, SQL 2000 Enterprise, SP4. I have one select using severals tables. One of them is XXX. The query run in less than a second and use clustered index on XXX. Execution plan show that. Now, I improve other different query adding a new non cluster index on XXX. After that the new query run faster. The first one run in more than 1 minutes with a lot of read ahead of XXX. However the execution plan still use the cluster index. There is no use of the new non clustered index at all. Statistics are up to day. Defrag is ok and so on. I was searching the reason and find nothing. So I have to delete the non clustered index and, of course, the first query back to normal and the second one run slow. What I'm missing? Fell free to ask for any question include both queries and execution plan if you like. Please don't question about statistics, defrag, space free, integrity, service pack, etc.