trimming problem in Acad

Hi,

Question directed to AutoCAD users. Have noticed that not
infrequently, when I try to trim a line with another line, often I
get the irritating message "Object does not intersect an edge".
Sometimes, zooming in to the intersection or regenerating drawing
helps. I have problem trimming line Handle=3F with line Handle=40
below: (both lines in plane x=155)

Handle = 40
from point, X= 155.0000 Y= 265.0000 Z= 450.0000
to point, X= 155.0000 Y= 265.0000 Z= 440.0000
In Current UCS, Length = 0.0000
3D Length = 10.0000, Angle from XY Plane = 270
Delta X = 0.0000, Delta Y = 0.0000, Delta Z = -10.0000

Handle = 3F
from point, X= 155.0000 Y= 25.0000 Z= 440.0000
to point, X= 155.0000 Y= 435.0000 Z= 440.0000
Length = 410.0000, Angle in XY Plane = 90
Delta X = 0.0000, Delta Y = 410.0000, Delta Z = 0.0000

The lines should intersect at point:

_id Specify point: X = 155.0000 Y = 265.0000 Z = 440.0000

These two lines definately intersect at point x=155 y=265 z=440 as
confirmed by an inquiry on the ID of both points above. How come try
as I might I can't get the line to trim?

I have tried extending line Handle=40 down to below z=440, still no
luck.

Is it me stupid or will this be a point for Acad haters to bash Acad?

Thanks

Alex