The Data Integrity Checker analyses the data being used in MT4 backtesting and reports on common problems: missing bars in the data, incorrect spikes in prices, .fxt files exceeding 2GB (which cannot be correctly processed by MT4).
The Data Integrity Checker watches for problems in the historic data being used by MT4's strategy tester.
You simply run a backtest of the Integrity Checker EA. This generates a report which watches for the following problems: