Without the OS CD, even the most minor of repairs can result in a busted OS. This scenario is best avoided since people get more than a little upset when you go from an annoyance to a machine that no longer runs.
Fix the base issue first.
PS. The usual be free from parasites would have been my response if the CD was available.
These Parasite removal programs can also SCAN. CWSHREDDER pretty much just removes such, but the others can just scan then ask if you want to remove such.
However, my policy needle on the pest-meter is pegged at zero tolerance. I eject all that these five tools find.
http://reviews.cnet.com/5208-6132-0.html?forumID=32&threadID=1313&start=0 notes the five scanning tools and removal tools that are fairly safe. If one does encounter an issue, its always been damage done by the MALWARE. The most common issue being Layered Service Provider replacement which you can use LSPFIX (Hint: use http://www.google.com to find).
The thread has follow on discussions about new links if you don't want to use Google to find an item.
PPS. All the tools are free.
I will be checking out a friends computer in a few days. All updates have been done for the computer from Windows Update. I don't know any details of the process, ram, etc but my question might be general enough to get an answer without it. She can bring up a web site on the internet explorer but when she clicks any links, she gets another internet explorer pop up and it is just blank and sits there. Is there a setting under Tools, Options, Advanced that might be causing this? It was given to her and there are no cd's to do a reinstall of Windows and I am not that familiar with it. Any help is definately appreciated. Thanks. Jeff