keyboard filter driver in 2k/nt

Hi everyone:
   i use a keyboard filter driver to intercept some specifical keyboard strike , everything seems well except that when i repeatly press the key been intercepted and without touching any other keys, the screen saver will activate. i intercept the key strike in the filter driver\'s IsrHook( called by keyboard controller\'s isr), and if the specifical key is pressed ,i queue a DPc ,where i call PoSetSystemState, but it doesnt work?
 
Could anyone here help me?????

Hiiiii any one here have some clues?????? i really need ur help.

1、试图从键盘驱动的isr模拟特定按键似乎不妥，特别是用usb、1394之类键盘的时候，这时你的一个dpc就可以让该总线的驱动停下来。换个中断级低一点的试试。
2、激活屏保说明你调用PoSetSystemState的时候要么参数不对，要么系统环境不对（主要是中断级的问题）

谢谢FT.S
   我没有在iSR中调用PoSetSystemState,而是在iSR中QUEUE一个dpc,在dpc中调用PoSetSystemState的.我看kbdclass中也是在ServiceCallBack中调用PoSetSystemState的.(而ServiceCallBack是在i8042的dpc中被调用的).不知还有什么其他的方法.
    另外我用的参数是ES_USER_PRESENT,也是参考KbdClass的.
    请指教,谢了,很急.一定给分

还有谁有什么建义？？？