hi, i've got the same problem,it started 4 days ago,i have an iphone 4s on o2 not jailbroken 64gig.i have had no problems at all fair battery life,had it for about 4 months but now most apps crash at random and the phone goes to home screen,i've done many hard re-sets i have also done a factory re-set but no joy in fact its getting worse,my next and last hope is to do a restore on itunes,any other sugestions would be most welcome.