This is usually a windows problem with a corrupted config file. 

Note that in VelociDrone 1-12 this particular bug is no longer possible, if you are having throttle issues it is more likely to be a calibration issue with the transmitter / controller than a config file issue.

Most instances of this problem are resolved by going to c:\users\<your-user-name>\appdata\locallow\velocidrone\velocidrone

Delete everything in this directory and then start the simulator and the problem should have cleared.

Appdata is a hidden directory so you may need to turn on the hidden files option in windows explorer to see it.