Few weeks ago I switched to gcc 4.2.1 (sjlj) and I got some issues with the debugger (gdb).
In the MinGw mailing list I saw the message
http://sourceforge.net/mailarchive/message.php?msg_id=46D2BF3D.5040709%40cox.netIt was discussing the same issue osbserved in my environment with gdb,
and in which it was suggested a workaround: Use -gstabs instead of -g.
Following this advice my gdb issues disappear.
Hopefully this helps somebody (I saw several posts about gdb issues).
Max