Trojan??

[haele]

8. According the the internets, it's pop-up adware to get you to download spyware.

There are various ways of getting rid of adware pop-ups, most of which require you restart in safe mode after you've found a good spyware/adblock program.
I tend to use Microsoft security essentials and an adblock program, so I haven't had to deal with this, but a good starting point is to look up the RDN/Trojan.worm Infection pop-up and see what's out there to remove it safely.
But it doesn't really do anything until activated, so you're still good for now.

From Virus Research.org.

The RDN/Trojan.worm Infection pop-up is an annoying message. Take it as a sign. A sign that your computer needs to be cleaned immediately. The adware behind this pop-up is quite hazardous. It is trying to lure you into downloading questionable software.

Other people will probably chime in with a better recommendation, but I'll at least commiserate with you...

Haele