Possible deadlock when gdb calls 'SuspendThread' function

[Jose Manuel Pulido]

Hello all. I'm using gdb 7.2, release version to debug a program written
 in c++ and compiled with gcc 4.5.0 in a MinGW environment under Windows
 XP SP3 32 bits. 

This is how my debugging session goes on: I usually attach gdb to my 
program when it's already running (gdb --pid xxxx), then gdb takes a 
couple seconds to show the interactive prompt and I enter 'continue' 
after (possibly) setting one or more breakpoints. 
My program keeps running and if I enter ctrl+c in the gdb console, 
sometimes not only gdb stop responding, but so does my program and 
Windows explorers renders unable to launch any new window. I can't even 
launch a task manager to kill gdb or my program. This, however, doesn't 
happen always, but roughly in the 20% of my executions.

If I manage to kill my program's process when this happens, both gdb and
 explorer regain their responsivity and gdb shows a lot of console lines
 at once, but the first of them is the following one:

'warning: SuspendThread failed. (winerr 5)'

Online documentation on SuspendThread states that a deadlock condition 
can occur if the thread being suspended owns a synchronization object. 
My program is GUI based and has some worker threads that use mutexes and
 system wide critical sections. Yet, I tried disabling every mutex and 
critical section in my code, but that didn't work out. 

The thing is I can debug other programs without any problem, and I've 
used to be able to debug this one as well, but I fail to understand what
 might be causing this. Reviewing the changes in my source code during 
the last two months, or selectively disabling functionality, but nothing
 of that helped.

I thank in advance to anyone that might read this and give a piece of advice. 

Regards, Jose.