Q:

Qt Creator hangs in Ubuntu Virtualbox

I have a very weird problem. Ive got a an Ubuntu 14.04 running on VirtualBox 4.3.20 r96997. I installed QT Creator a while back and was working with it fine until today. Now when I try to start it, the screen is completely unresponsive, and it endes up freezing (just the QT Creator screen, ubuntu keeps working fine)
I have read in a couple of places that this could be because the welcome mode doesnt play nice with virtualbox 3d hardware acceleration:
Why does Qt Creator 3.0.0 Welcome Mode not work in VM?
http://qt-project.org/forums/viewthread/37412
But im starting ubuntu with the 3d hardware acceleration disabled, and Ive also tried starting it direcly from the terminal by going to the install folder and doing:
./qtcreator -noload Welcome -noload QmlDesigner -noload QmlProfiler

But it also freezes. And the weird thing is that it worked yesterday, and I havent installed any updates or changed the system, it just appears to have stopped working.
Any suggestions?

A:

Posting my comment as an answer, since OP confirmed it works.
Delete the configuration directory for QtCreator - it's somewhere in ~/.config/

A:

In the ~/.config/QtProject folder is a lock file (QtCreator.ini.lock). This is the reason why QtCreator freezes. By removing only this file QtCreator will not freeze any more and all the configurations / settings are still there. 

