If I use function "Text Importer ..." (menu Tools) then PLSQL Developer freeze (under Windows 7) tell "Not Responding" in title bar. This freeze comming after import processed about 1700 rows. This behavior is both for buttons "Import" and "Import to Script". But in the second instance of PLSQL Developer I see that first instance still working or the SQL file on disk increasing...
Code
PL/SQL Developer
Version 8.0.4.1514
01.59953 - Unlimited user license
Windows 7 (64-bit) 6.1 Build 7600
It's always done that for me, too... It *appears* to be frozen, but the import continues... it's just that the window is no longer being updated. It will update again (and un-freeze) once the import is complete.