2000 Renault Clio wont start

Electrical problem
2000 Renault Clio Manual 72000 miles

Now and again my clio 1.4 sport wont start , the stop light , handbrake light and petrol light will be on , without any keys in the ignition , If i leave it for an hour it usually starts , Thinking about it , this happens when a few hours after its rained or been washed . It has an immoboliser and that can sometimes set the alarm off go off for no reason . Any advice gratefully received .

Thanks Joanne