Im not sure of what screen your seeing at bootup, but one simple thing to try is to go to your start menu-programs-startup and see if the program that is annoying you is listed in there, if it is, just delete it..it is only a shortcut so you wont be doing any damage..
The next option is using MSConfig from the run command..but that gets a little more tricky and you have to be absolutely sure as to what your looking for...
Try the start up folder thing first and see if that helps..
Good Luck,
Zero.