Flashing LCD Screen X21

[Ozthinkpadist]

Dear Forum....I have an old X21 which I'm hoping to restore to health. Problem is a badly flashing LCD screen. Machine will work OK for about 30-60 minutes, then screen begins to flash (ie blinks completely off) at a reasonably rapid rate (maybe 10 time every 5 seconds on average). Also I've noticed that everything goes crazy when I try to connect an external monitor - my thinking is that its the video card but would be interested in others thoughts before replacing. BTW unit is running XP Pro, 384Mb RAM. Many thanks for advice. Cheers Anthony