Can watching TV mess up your laptop? No. As previously suggested, your Internet connection may not be fast enough but that shouldn't cause "all hell to break loose," but rather just slow the connection. Think of the your Internet connection as a water pipe. If you're taking a shower and someone starting using the water in another part of the house (like filling the washing machine). The pressure in the shower drops. Same thing kind of happens with your Internet, and if the "pressure" drops too far you'll get messages from your browser like "can't connect," "waited too long for a response," etc.

The solution is to up your connection speed. If you don't have a contract with AT&T or are long into it, you can probably work out a deal for more speed at little or no cost. Heck, in some cases it can actually cost less. Makes no sense to me but that's how these companies work.