>When I try to execute a SQL transaction in Visual Basic using Delete from Receipts where ... sentence, in a table with a lot of records (near to 2,000,000) it return a error message "timeout expired".
>When I try to execute this sentence in SQL Analizer it ends in 2 or 3 minutes.
>Which is causing the tha trasaction abort?. Is there a way of changing the value of this timeout?

Which data access method are you using? In VB, see the CommandTimeOut property. Also, you should consider checking your indexes. It seems quite long!