>I reindex all the time my table, but after some days I always get an index corrupted. Proof: when I do a select with a reference in the where clause
>to the field indexed, the computer freeze in this specific case.
>
>Someone can tell me why an index may be corrupted, so often?

Craig Berntson has an article on his web site on this:

http://www.craigberntson.com/Articles/kb005.htm