Help! Windows cannot find Wltrysvcs.exe???

When my desktop starts up, an error message appears saying that "Windows cannot find Wltrysvcs.exe. Make sure you typed the name correctly and then try again. To search for a file, click the start button, and then click search." Sometimes after this messgae appears, my PC will stop ruinning at the start-up and the desktop's icons never appear. Does anyone know what could be going on? I'd appreciate any help. Thanks...