Switching to Thread -1208416576

Hi,
I have a program in Qt 4.3 and it is running. I used a thread in that program. But when I run the program it became crash. It display an error message like this, when I use gdb to find the error. The error message is like this,

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1208416576 (LWP 24020)]
0x012a2186 in QSlider::mousePressEvent (this=0xa134498, ev=0x8097aab)
at ../../include/QtCore/../../src/corelib/kernel/qcoreevent.h:241
241 inline void ignore() { m_accept = false; }
Current language: auto; currently c++

Please help me to solve this probs.