Form "Procesando..." que no se congele

[roman]

En realidad no sé, Felipe.

Se supone que un hilo no puede interactuar con componentes de la VCL y esto incluye componentes de acceso a datos como un Query, aunque el manual dice:

You do not need to use the Synchronize method for the following objects:

Data access components are thread-safe as follows: For BDE-enabled datasets, each thread must have its own database session component. The one exception to this is when you are using Microsoft Access drivers, which are built using a Microsoft library that is not thread-safe. For dbExpress, as long as the vendor client library is thread-safe, the dbExpress components will be thread-safe. ADO and InterBaseExpress components are thread-safe.

When using data access components, you must still wrap all calls that involve data-aware controls in the Synchronize method. Thus, for example, you need to synchronize calls that link a data control to a dataset by setting the DataSet property of the data source object, but you don't need to synchronize to access the data in a field of the dataset.

por lo que parece que el Query está a salvo.

Hice una pequeña prueba con dos ventanas y no tuve problema, pero había que ver con más detalle qué estás haciendo tú. Quizá estés interactuando de alguna manera con componentes visuales o que no son thread-safe.

// Saludos