Compile c++ code with IDE, error at the second time - c++

Question

I'm a fresh c++ user in Windows 8 system. I have installed MinGW and setup the environment variables. I create the simplest hellow world code as below
#include<iostream>
#include<vector>
using namespace std;
int main(int argc, char **argv)
{
cout<<"hello world"<<endl;
return 0;
}
It works well at the first time, but when I do some small modification, for example delete "hello", and then build and run the project again. I found that the program will keep running without end. The command line keeps showing:
Current working directory: C:\Users\cr\Documents\project\helloworld\Debug
Running program: le_exec.exe ./helloworld
If I try to build it again, it shows
make.exe[1]: Entering directory 'C:/Users/cr/Documents/project/helloworld'
C:/Users/cr/MinGW/bin/g++.exe -c "C:/Users/cr/Documents/project/helloworld/main.cpp" -g -O0 -Wall -o ./Debug/main.cpp.o -I. -I.
C:/Users/cr/MinGW/bin/g++.exe -o ./Debug/helloworld #"helloworld.txt" -L.
c:/users/cr/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: cannot open output file ./Debug/helloworld.exe: Permission denied
collect2.exe: error: ld returned 1 exit status
make.exe[1]: *** [Debug/helloworld] Error 1
helloworld.mk:78: recipe for target 'Debug/helloworld' failed
make.exe[1]: Leaving directory 'C:/Users/cr/Documents/project/helloworld'
make.exe: *** [All] Error 2
Makefile:4: recipe for target 'All' failed
====1 errors, 0 warnings====
I could not even delete the executable file "helloworld.exe" because it is using in 'System' until I restart the computer.
Update:
I can compile it in the command line:
C:/Users/cr/Documents/project/helloworld>g++ main.cpp -o test.exe
C:/Users/cr/Documents/project/helloworld>test.exe
It will then keep running until I close the command line window. If I open a new command line window and compile the file again. There is no problem.
Update2:
Problem also happens when I compile the cpp file the second time even if the file has not been edited.
C:/Users/cr/Documents/project/helloworld>g++ main.cpp -o test.exe
C:/Users/cr/Documents/project/helloworld>test.exe
hello world
C:/Users/cr/Documents/project/helloworld>g++ main.cpp -o test2.exe
C:/Users/cr/Documents/project/helloworld>test2.exe
It keeps running here.

Answer 1

Thanks all, I struggled with it for a whole day. The problem is anti-virus software...... I set it inactive and all things do well...
I don't want to point out what this software is, but just want to give out a reminder for this problem....