Hi Panteha,
I am currently using 2008 Civil 3D.
All layers are visible, none are locked/turned off/frozen.
Imageframe is set to 2. (tested setting imageframe to 0 & still got the same issue)..
The vertical lines are black & .25mm wide...
As I didn’t prepare this drawing & one of my juniors did, I have dug a little deeper..
As I now I have had the time..
There are actually 2 images (both were imageclip), I turned off the clip, & re built the vports from one to two to clip the image via the vports. plot..... still the lines on the lower image..
I focused in on the lower image that was having the line come up, opened it up & was a little freaked out by the use of brackets in the file name.. eg.087611007_XIMG_Figure 21b (seepage_0kpa).jpg
So I used my image program (SnagIT - highly recommended, or Jing is freeware version).. Save As the image & removed the brackets..
SUCESS.. YAH!!!

Thanks for your support...