You pretend to sift through the cards, but really your thoughts are on the whole mysterious affair. After a few tense moments you go back to the librarian's desk

"Sir - I have this friend who knows loads 'bout computers. I could bring him in here, and I bet he can get rid of this virus."

The librarian merely stares at you. Something tells you that he knows perfectly well there is no virus, and he is considering which answer will serve him best.

"Sorry, my mind blanked out, would you repeat what you said," the librarian said, shaking his head. Maybe he isn't faking it, but don't count on it.

"My friend - fix the computer."

"Oh, of course, I'd be delighted if he would spare some of his time to help out this old under-funded library." You look for signs of lies, but all you see is sincerity.

"Sure, I'll ask her to come over in the next few days." You go back to what you hope looks like your own buisness.

In the hopes of calling the librarian's bluff, he called your own. You have no friend who is any computer expert.