各位,急救!这到底怎么回事?任何程序都不能正常运行,急死了!!:(

[cnbill]

各位大侠,我编译程序时通过,但运行时总是出现如下错误,请问是什么原因?
急救!!!

D:\>javac BasicsDemo.java

D:\>java BasicsDemo.class
Exception in thread "main" java.lang.NoClassDefFoundError: BasicsDemo/class

源程序如下:
public class BasicsDemo {

public static void main(String[] args) {

int sum = 0;

for (int current = 1; current <= 10; current++) {

sum += current;

}

System.out.println("Sum = " + sum);

}

}