cuda programs can't run(occupy 100% CPU)

There is a strange problem. I have just deployed cuda on Ubuntu 9.10 in the afternoon, and programs in “src” directory run well then, such as bandwidthTest. However, I couldn’t run any programe at night, even after reinstall cudaDriver/cudaToolkit/cudaSDK. Aftar cuda programs start, they occupy 100% CPU, and can not do further work. It seems that they trapped in an infinit loop. Can somebody tell me why and how I can solve them, Thanks very much!