My DS1052E does this too, and it's incredibly annoying. Though I only noticed my unit do this after I hacked the firmware to operate at 150 MHz bandwidth. So--for me at least--it does seem to be reversible when changing the bandwidth back down to 50 MHz. The odd thing is, it doesn't always act up, some days it works fine, then others it's almost impossible to use the soft keys and sometimes the timebase rotary encoder adjusts in the wrong direction.
So if you have hacked your scope to 100 or 150 MHz, try reverting back to the stock bandwidth/model and see if that helps.
If you haven't hacked your unit or opened it up, Rigol is actually really good about accepting RMAs to fix problems if it's still under warrenty. You pay to ship to them and they pay to ship the equipment back to you.