I discovered that episodetweaker was crashing whilst trying to find c:\program files\devnz\gbpvr\config.xml.
As I am on win7 64bit, my config.xml is in c:\program files(x86)\..... However, I had created a c:\program files\devnz\gbpvr folder as this is where another utility (vidimport?) was looking to import an xml file containing recordings.
So, I removed the incorrect c:\program files\devnz\gbpvr and episodetweaker and all these wonderful utilities now work perfectly.
Silverstone LC17 Case,
ASUS P5Q, Intel E7200, 4GB RAM
Blackgold DVB-T2, ATI 7750, Windows 7 64-bit
SAF codec pack,Sony 40" Z5500