For a few days, I let my brother use my MacBook Pro. I did not have LimeWire installed on it, nor did I need it because the home computer already had it, not to mention that my brother had it on his laptop.

However, without my permission or knowledge, he installed it. As soon as I found out, I got rid of the program from the system by removing all the folders for it and deleting shortcuts.

Now, the problem is that my MacBook experiences a constant state of lagging. I will be typing a sentence (like this one) and by the time I'm done typing, the computer claims I'm half-way done and slowly adds a single character at a time. All my other programs have been lagging on me, including Safari, which makes my scrolling very choppy and inconsistent and also take a long time to change the cursor while hovering over links.

My brother swears that he did not change any other programs, settings, and also did not download additional programs. All the files that he downloaded (sadly all illegal MP3s, which I deleted) were all legitimate.

Does anyone have a suggestion or a solution to get my system performing the way it did? I'd be very appreciative...