[solved] some misunderstanding while using qt

I’m new in Qt(abaut 1-2 weeks of using it). I’m writing some gui application.
question:
all slots of GUI-objects like QMainWindow QDialg QStyledItemDelegate are executrd in GUI threads, aren’t they?
if so i have some problem… i have a tabWiget and a timer to update data on it. when user changes tab application crushes with C0000005 – Acces Voutation in QTCore.dll this problem is OS-specifik actualy only on Windows XP x86
some more info
i have a QListView with my own model
when user selected a new QListView Item data on tab wiget should be changed.
I implemented it in such way:
i connected to QListView clicked(const QModelIndex &) Signal from there get index.row() stored it in int value
QTimer was set for 1 sec to update tabs…
My be any one will give an advise for better realisation…