There is a lot of misinformation with HDMI. First the interface was never designed for the cable lengths we are using, it was designed for a max cable length of 5 meters (16.5 feet) with passive cables. If you have a system work with longer cables than consider yourself lucky but don't be surprised in the future if it doesn't when we get sources that start using the full bandwidth of HDMI. 1080P uses a little less than half of the HDMI bandwidth.
There are boosters and equalizers as well as other types of products for long runs. A LOT of it will be a crap shoot on whether it works or not. There can be many problems with HDMI and some of these only solve one of them. If it is the one that is causing your problem you are in luck. If not back to the drawing board.
We have found a few products that work very well. One is what is called a signal restorer and it solves most HDMI problems. Ethereal and Spectrum Electronic Solutions make them. They are not as cheap as the bargain ones but they WORK!
Other solutions for long runs are Baluns with either dual runs of Cat6 wiring or fibre optics. I prefer the fibre optics but it is pricey. For runs less than 100' I'd use the signal restorer. The quality of cables do make a difference with HDMI. Expensive doesn't mean better either but cheap is sometimes just that. I recommend checking
www.dplratings.org for companies that pass their testing.
BTW, there has not been one passive cable longer than 6 meters (19.8 feet) that has passed their testing at full HDMI bandwidth. So you might get lucky with 1080P and a longer cable now but expect to add some type active circuitry to correct the signal in the future.
Bob