Hi, My company use a 3rd-party Access97 application that runs on a SQL 7 database. I Have access to the sql server, but not to the application code so I can't tune my queries, juste the SQL server. My problem is as follow: There is a task most users do that can take them from one hour to 4, depending on the speed of the app that day. Simply put, the form loads 3 sub forms which queries 3 tables that are quite large (1 000 000 records, 8 000 000 records and 760 000 records) One day, I started the profiler, caught what looked like the query in question and ran it through the query optimizer. The optimizer suggested a new index, which I created and bam! the screen that usually took 40sec to 1 1/2 min to refresh was below 1 sec! But... (there's always a but...) after one week, the problem returned. So, I deleted the index and bingo! 2 days of good performances. Since then, I'v been creating end deleting indexes every other day or so and every time the performance returns to normal. I usually touch only the 2 smallest of the 3 tables. Any idea what can cause this and what can I do to maintain my performance at peak level?