i just had the same problem this morning. tried couple of hours solving it. compilation debug = true, autoeventwireup = true...etc..etc.. nothing worked. i restart my pc, reset devsetting of visual studio, and all other things that comes up to my mind. still no luck. i am using windows vista. the solution? go to start menu, find the visual studio 2005, right click then click properties. in compatibility tab, check "Run this program as an administrator" that's it, i was going crazy this morning but the solution turned out to be really simple. hope this helps