I don't know what the first person to respond to this is trying to suggest. He says press the CTRL key. It works for him. How he knows this would work for you I have no idea, as your problem is not at all clear. In addition, he appears to be advertising his own software. So follow his advice with caution.

Your problem. Does the popup say anything else? Is there any other clue about what this ''plugin'' is?

What happens to the popup window, can you close it? If so, what happens then, does some other program open?

What measures do you take to protect yourself from viruses, spyware, adware, and hackers? Have you done a scan recently for any malware you may have picked up?

When did this popup first appear? Why did it appear? I mean, what had you done immediately before it began, (installed programs, surfed the internet)?

Have you tried a System Restore to a date before this popup appeared?

As you can see, lots of question asking for more details, so the answer, ''Press the CTRL key'' probably is not the best advice.