If the front-panel buttons work but the remote doesn't, it's very likely that infrared interference is to blame. The interference drowns out the signals from the remote.
Possible sources of interference are plasma or LCD TVs, energy-saving or fluorescent bulbs, direct sunlight, or PCs with IR ports enabled. If you have a LCD TV, adjusting the backlight may help. Other than that, it's a case of rearranging things or shielding the IR receiver on the box so it doesn't pick up the interference.
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