Just adding myself to this issue as it drives me nuts.
Mine has done this since I bought the fvp-4000t (along with other glitchy behaviors). Covering the IR sensor didn't work for me, I concluded it was something to do with the CEC protocol over the HDMI connection even though it's turned off on both ends. It's definitely more of an issue when I'm watching youtube or netflix on the TV.
If there was an option to stop it automatically buffering to the hard drive, it might not be as noticeable or problematic.
As it happens, I've come here today to see if the Humax BT youview+ boxes are as buggy as the freeview one as it's steering my decision on choosing their broadband and TV.
Just for reference, the TV is a Vestel made/Toshiba branded model which in itself is very buggy so I wouldn't put it past it to still be sending CEC commands even though it's set not too.