In the Schema Browser | Tables | Data tab, when retrieving data from various tables, Toad hangs (states, "Data Processing... 7 seconds") when certain tables are accessed, and the application has to be closed via the Windows Task Manager.
This can occur if the Oracle client on the machine is an older version than the database that Toad is connected to.
Data type in one of the columns is XMLTYPE and thus Oracle Client and DB Server must be Oracle 9i.
Use or Install an Oracle client version that matches the database version.
If a specific table in the 9i database has a column with the XMLTYPE data type, using an 8i or 10g client will cause this behavior to occur. The 9i Client must be used and set as default Oracle_Home.
NOTE: Data type XMLTYPE is exclusive to the Oracle 9i Database.