Question for Computer people

I have just bourght myself a Lilliput TFT-LCD Touch screen color monitor to use as an external lap top screen to use with moving maps . Problem is it starts to flicker after a couple of minutes . Mate bought one also and his is fine . So , we pluged mine into his 12volt system and it did the same . I then pluged it into my wifes car , and it was ok . Question is , will this screen need its own regulated power suply to get it to work ? It,s the only thing i can think of , that the diesel,s power suply is not constant , but then my mates works ok . Or is it in the programe to set the external screen up . Im sure it,s the power , but i carnt work out where the prob is , so if anyone has any idea,s , im all ears . Thanks .