T.v. repair

when operating set it takes several minutes for picture to appear, varying times from 4 to 5 mins and picture colour is now distorted, some times picture lost completely following sudden flashing lights on screen. then television switched off till digital cable box is re-booted. o.k for a while and then repeats performance when it gets hot I presume. Television purchased in 1995 and has had one small soldering repair 3 years ago.