If you ever receive such links, it is best to ask your contact if they meant to send it. If they did not type it themselves, then it means they have somehow been infected with one of these programs and you should
not click it under any circumstances, as it will then infect your computer.
However, if it is you who is sending the links, it means your computer has already been infected. If this is the case, make sure your anti-virus software and definitions are up to date and do a scan. If that doesn't help, search the forums as many threads about this sort of thing have been posted before and you might be able to find an answer there