Betfair's scalping strategy is based on opening multiple positions and closing them with a small profit. In a scalping strategy, the trader tries to catch small price movements and make money from them. You are supposed to place two bets in quick succession and then make profits from the gap between these trades.
Generally most issues with the Betfair website will be due to a 'caching' issue. This is when your internet browser holds 'out of date' information in the history folder, which conflicts with the page the browser is attempting to load.