Adware-UCMore detected by McAfee scan?

When I ran McAfee Scan it detected the above and I had it removed. My question: Could it have done any harm prior to removal?

Also on McAfee, if I am not using computer for about a week it tells me I am not protected and I have to download latest updates and run scan. I am afraid that during the unprotected times I might pick up a lot of viruses.

If it was detected, then no harm done. The times you’re unprotected are when the PC is off, your anti-virus updates as soon as you start, so no problems there either :)