I would never purchase an HDTV for their wireless features. They are still generally way too buggy, including some of the higher end models. It's probably the number one issue that arises.
Some possible fixes, of which clearly some will not always be possible/practical:
-Change the position of the router
-Change the channel of the router (other devices on the network can benefit from this too)
-Update firmware of HDTV if available from Manufacturer
-Make certain your router has most up to date firmware
-Add a wireless repeater (bridge), then utilize a wired connection (ethernet) from the wireless repeater to the HDTV. Quick and cheap to set up.
-Avoid wireless altogether, and improve overall performance/connectivity issues by simply going wired directly to HDTV (my favorite, btw) *If you are a Netflix user, this one will make you very, very happy. There are simply so many ways to hide cables now, it makes little sense not to go this route IMNSHO.