I've noticed that if two users try to run CUDA programs at the same time, it tends to lock up either the card or the driver (or both?). We need to either reset the card or reboot the machine to restore normal behavior.
Is there a way to get a lock on the GPU so other programs can't interfere while it's running?
Edit
OS is Ubuntu 11.10 running on a server. While there is no X Windows running, the card is used to display the text system console. There are multiple users.