I keep two ballasts, one digital and another magnetic, less than ten feet away from the television in my bedroom. I've never experienced any problems. The magnetic one is only a 400w, though. How many watts is the one you're using? If it's a 1k, it might be powerful enough to mess with your television. Digital cameras, cellphone cameras, etc., on the other hand, seem to get a little screwy when used near some ballasts, like Hybrid mentioned.

Are you seeing discoloration on the television screen? If so, it might be a good idea to move the ballast, or the television so they don't interfere with one another.