External Display problems after Lion upgrade

hello

have mac pro tower (circa 2007) , using external display (nec). since upgrading lion having display issues:

1. upon turning machine on, monitor doesn't display image. need force power off machine & turn on. sometimes, triggers image.

2. after machine has been asleep, go wake , computer wakes, no signal displays on monitor. have force power off machine & turn on.

i'm read of others here , there having similar issues. here experience or have possible solution? monitor should fine... it's related lion upgrade.

 

i'd general troubleshooting first;

reset pram
(hold cmd + alt + p + r @ boot, wait 'bong' several times, , release)

reset smc
(power down, take out power cable 10 seconds, re-attach)

fix disk permissions in disk utility

run fsck
(hold cmd + s @ boot, wait root: prompt, , type 'fsck -fy', repeat until says boot partition ok)

see if helps

 

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