I have a Vitek EH8 that has been running pretty much constantly for well over a year or so. It is starting to lag severely when I playback.  
  
Any thoughts on what may be causing it? Could the HD or some other part need replacing?  
  
I noticed it doesn't have RAM, per se, like in a PC yet the HD looks like one in a PC.  
  
I usually just restart it and that helps most of the time but it still delays when I try to change channels, fast forward, etc.