soldering help please

[sublime90]

ok i have my messiah 2 installed for about 3 years no problems ever (i installed it myself) now this 1 wire has come undone and simply will not stay! i solder it and its on good.....then i play a backed up game, everythings fine, i turn the console off the next day my copies wont load....that wire has come un soldered!!! this has happened like 5 days in a row now and its getting on my nerves, i used flux and everything. should i just discard that wire and put a new wire on? i need some help here because it simply wont stay soldered now, its just that 1 wire!!