Debugging error of a simple program

Hello Qt guys...
As a new member to this forum and a Qt newbie - no wonder I come across a few errors from time to time. When I tried to open a new widget project - it compiled and debugged properly. When I got into main.cpp of the widget and changed the code ( just anything ) it wouldn't debug and is giving me this error instead:

:: error: cannot open output file debug\HelloWorld.exe: Permission denied
:: error: collect2: ld returned 1 exit status

What is the reason behind it ? Thank you for any comments.

P.S. My Qt paths seem to be correct I guess. No problems with them..

Is your Hello.exe still running? I usually get this type of error when I forgot to close my program before recompiling it.

Thanks - that was the reason. Of course ( have just noticed ) you can close the process straight from the Qt output menu.

See if you can delete your HelloWorld.exe manually. If not, then you can be sure that an instance of your program still runs

Can you delete the output file (.exe) ?

Indeed guys...the reason was as 'ars' pointed out - that closing a process is a must on Win ( whether in task bar or Qt output menu ) I've just noticed the process closing options in Qt.

Seems to be working for the time being. Thx to all..