pop ups at boot up

Hi.My wife's pc gets these 2 pop ups every time she turns
it on: 1. ERROR MESSAGE: Run DLL32.exe bad image and
larger popup: 2. "The application or DLL
c:\windows\System32\2ndscrch.dll is not a valid windows
image.Please check this against your installation diskette".
Our younger son was monkeying with it and this is the
result. He denys it of course but she'd like to stop these
annoying popups. Anybody got an idea? Thanks, Allen