Moving to the Chest, is your best first option (after repair if that doesn't work), you can recover from moving a file to the chest, you can't recover from deleting a file (that you don't think is too important) if you find you have made a mistake.
It also gives you time to investigate the problem, ask a question, etc.
The location seems strange, being within the avast4\data folder, unless that were within the avast4\data\chest folder. There is no prompt[1].htm in the location you gave in my avast4\data folder
It will probably be worth a visit to Eddy's HiJackThis Info and Analysis page,
HiJackThis log file analyzer and follow the directions there for HiJackThis and get back to us if you need more help....