Hector,
Since no one else is experiencing this problem, I have to agree with Vic that it might be a corrupt library. It may actually be your application-specific data environment library that is the problem. I recommend creating a new data environment library and saving the data environment created by the builder in this new library to see if the problem goes away.
Regards,
Kevin McNeish
Eight-Time .NET MVP
VFP and iOS Author, Speaker & Trainer
Oak Leaf Enterprises, Inc.
Chief Architect, MM Framework
http://www.oakleafsd.com