The “access denied another project is using this target”
happens when one of your debug sessions gets interrupted and
LabVIEW thinks a session is still running when it isn’t.
When this happens go to the Project Window,
Right-click on RT CompactRIO Target,
You can reset the cRIO too if you like.
The waiting for target to respond error is usually the computer’s fault rather than the cRIO.
Something in the IP address/netmask, multiple active NICs, virus checkers/firewall settings disturbs the network connection.
It can also be caused by the cRIO being too busy with the robot program to respond the the commands to deploy new code. On work around for this is to use the imaging tool to set the No App switch, apply settings, deploy your new code, unset the No App switch, apply settings.