Many problems with QMP, especially crashing or freezing on launch, can be at least partially resolved by starting QMP in safe mode. This will start QMP without loading any plugins.
To start QMP in safe mode, you have to create a shortcut to QMPlayer.exe with /safestart appended to the target of the shortcut. You can use the existing QMP shortcut icon on your desktop, start menu, or quicklaunch bar. Right-click on the icon and choose Properties. In properties dialog, choose the Shortcut tab and in the Target box append /safestart to the box's current contents. The result should look something like this:
"C:\Program Files\Quintessential Media Player\QMPlayer.exe" /safestart
Click the OK button and launch the program by clicking the icon.
Bugs may be submitted to the bug tracker. This link my also be found via the forum.