Newer trojans are getting very smart, will install loaders that run automatically, and can’t really be picked up by AV, as they don’t have any specific signature to work with.
Also can install as part of OS, and prevent removal except in safe mode. To clear your current infection you will need to determine exactly which trojan has infected you, then go to one of the major AV sites to find out best way of dealing with it. On a network these can be really deadly, as they will spread by many means and will not show up on some systems, just sit there ready to re-infect any system you manage to clean. To deal with this type of outbreak you need to take all systems off network, and only bring them back on, one at a time, once you are sure they are clean.
It is actually a trojan horse downloader or spyware programs installed in your browser or computer. This problem could be fixed using your updated and latest anti virus software program or you can reinstall your browser to have a newly installed and virus free internet browser.