Laurie downloaded some tax documents from DocStock.com and now she's having a variety of problems on her computer. Leo says that docstock.com is a legit site, but it's possible their website got hacked or a malformed PDF was installed onto the site. The strange tool bar in her browser is a bad sign.
Laurie could get someone to remove it (and she's tried), but it's likely there's other stuff going installed and going on as well. So the only way to really be sure is to back up the data, format the hard drive, reinstall Windows from a known, good source, and run updates.
She should also find someone better to help her out. Leo says to look around, ask others, and if they don't immediately recommend the solution above, move on to another person. A good high school student could probably do a better job than Laurie's tech guy.