how can i fix vauxhall corsa 1.0 ?

display all dissapeared but lights, windows indicators etc still work. stopped and car stalled and wouldnt start again. checked fuses-all ok. fiddled around checking for anything loose and still all ok. car would start but then die if you pressed accelerator. slammed the bonnett - display lit up again and engine started and ran as normal...what is loose, where do i find it and how can i fix it and stop it happening again?