As an (out-of-work) computer professional, I’ve found that revealing my profession in a conversation is a recipe for disaster. I imagine it’s much the same way for doctors and lawyers. What other jobs get this sort of attention? Do people sidle up to civil engineers and ask them for help building bridges?
It’s not that I mind random questions about computers. Not at all; I’m usually perfectly happy to talk about general computing and technology issues—although I sometimes suffer from the inability to reduce my knowledge to a basic enough level to actually have a conversation—but the assumption that I not only am I interested in being free technical support, but that I will somehow be able to help fix the problem with no access to the computer, and armed only with a few barely-remembered details (“it doesn’t work”), annoys me. Stop it!
For that matter, I’m a software developer, and the skill set isn’t necessarily applicable. In my case, I happen to have a good deal of experience with personal computer support, but I know plenty of very good programmers who wouldn’t know a hard drive from a power cable. It’s like conversationally asking a criminal lawyer for help with your divorce. He just isn’t going to be all that helpful.