System Exclusive Applications

[mattb1409]

I'm trying to write a password protection program, that will load up before Explorer (at a similar time to the network login prompt etc). I can get the program to load at the right time by uing the Local Machine\..\Run regkey, but then the rest of the system continues to load. How can I get the system to pause, while my application keeps running? Even it's just by sending it into a while loop I don't care as long as my application can accept keyboard input. I know it can be done because I have seen applications that do it, but I don't know how!

Thanks for any help you can give!

Matt