Programs Don't Show On Taskbar

I have a gateway notebook running Windows XP. There are 2 user accounts, each with administrative rights. I recently installed SP2, defragged the hard drive, and cleaned up some spyware and adware with spybot and adaware. I am also running Norton Anti-Virus and all definitions are up-to-date. (This is my college daughter's computer). All ran fine after doing this, but after the next boot, the taskbar completely disappeared. I was finally able to get it back, but only by selecting the quick launch toolbar. If I deselect the quick launch tool bar, the whole taskbar goes away. The real problem is that programs no longer show up on the taskbar when they are opened (Word, Excel, IE, Trillian, etc). And, if I open a program, and then minimize it, it goes away completely as though it were closed, but if I open task manager, the application is still running. I have to close the applications from task manager. The really odd thing is that this is only happening on one of the user accounts (my daughter's). The other user account is functioning normally. Short of creating an additional user account or using system restore and starting all over, does anyone have any ideas on how to repair this?