Trojans are malicious applications that pose themselves as legitimate software in order to trick users to install them. Once on the victim's machine, it may run any number of malicious process to steal vital information or inflict damage to other software.
RogueDrop is responsible for false Windows alert messages and false Internet explorer warnings to force the user to download Rogue Applications. It also drops many files masquerading as malware files so that SpyAway, PerfectCleaner, SystemStable can detect them to convince the user to believe the computer is infected.
More details can be found at http://blog.spywareguide.com/2007/06/rogue_security_applications_be.html