buckling harwood floors
In my experience, which is admittedly limited, you never want to glue hardwood to cement. Most hardwood manufacturers will tell you that you shouldn't put hardwood over a cement subfloor to begin with, but if you do you want to float it on a plywood subfloor or on plywood float strips. The problem is that the wood expands and contracts at a different rate from the cement, so when it does so through the season, you end up getting buckling and separation. Your best bet for a long-term fix is going to be to pull out the entire floor, salvaging as much as possible, and put in a plywood subfloor over the cement before nailing the hardwood to the plywood.

Having said all of that, I am not a contractor or professional floor installer, and I realize this could get very expensive very quickly. Unfortunately, IMHO, you're in a bad position thanks to faulty information from Home Depot, and your only good way out is the expensive way.