My ISP at home, WOW, has started filtering DNS lookups and redirecting unresolvable names to their own search site. I found a lengthy discussion of this issue here. Basically, if you misspell something, a Yahoo search results, and they must be getting some money from Yahoo for the ads that you might click. WOW considers this a "feature".
The trouble that this causes is other local resources are never searched for in a workgroup because everything resolves as a valid internet name.
A suggested solution is to use a DNS server other than that provided by my ISP. The ones I chose were 220.127.116.11 and 18.104.22.168. These belong to group of public DNS servers in the 4.2.2.x range where x is between 1 and 6. The two that I choose had the shortest ping times of the group for me, 9 ms each. A good discussion on the origin and current ownership of these DNS servers is here.
While not guaranteed to work and be free to the public forever, these servers have been around for years and, according to the comments, have been used techs and consultants all the time.
It is still better to use a DNS operated by your own ISP if they can provide one which is fast and doesn't contain unwanted "features". But if they don't, then try one of these alternates.