I have a Dell Dimension 8300 and I don't have a "dadapp", but a Google search shows that is a customisable key applet for a Dell laptop, so I expect you have a Dell laptop.
Originally you said your problem was with Search Assistant and QuickLaunch appearing in your taskbar.
I was hoping that any of the items in the start list would have been the cause of these two items in your taskbar. But I am now not sure what you mean by taskbar.
You say they appear in the taskbar when you start the computer. Which part of the taskbar?
From right to left you have;
1] The System Tray - where things like your clock, your firewall and antivirus are placed.
2] Left of that is the main taskbar where, if you open any programs like Internet Explorer or Microsoft Word, they are displayed in this taskbar.
3] To the left of this, and just right of the Start button, on some computers - A QuickLaunch bar where you can load shortcuts for those programs you use often.
Whereabouts in the task bar do these entries for Search Assistant and QuickLaunch appear?
If they are in the main task bar area, then the programs are loaded already, and clicking them in task bar should bring those programs back up to the desktop. If thats the case then you should be able to see what programs they are, and where they come from.
If they are in the System tray, then you can right click each icon, and see what they are. If that doesn't work, double click each item and see what program appears.
If they are in the QuickLaunch part of the taskbar, then it's easy enough to remove them from therem either by right clicking the icon and selecting delete, or right clicking an empty space in this area, selecting "Open Folder" , and in the C:\Documents and Settings\Your Name\Application Data\Microsoft\Internet Explorer\Quick Launch folder that appears, deleting the shortcut from there.
If they reappear in the QL bar the next time you start your computer, you must find which program they belong to and explore that program, eg Options, or Preferences, or Settings, and de-select, "load on Start-up" or similar option.