Measure and Polyline problems

We use AutoCAD R2004 here at work. I have a couple of questions,
hopefully someone can help with.
The "MEASURE" command is supposed to place points on objects at the
specified interval along the selected object, starting at the endpoint
closest to the point you use to select the object. I have a polyline
100' long, with "0" Z coordinates. It's drawn with a large radius
(over 12,000'). I want to measure 62' along the line. I use the
MEASURE command, and pick the line about 8' from the left end. It
measures 62' from the RIGHT end. If I zoom in close, and pick the
line about 1' from the left end, it will measure from the left end.
This type of thing happens rarely, just often enough to completely
screw up something very important. Anyone know why this is happening?

Polylines give us lots of problems. I can have two polylines meeting
within .00005, and can't join them. Setting the "fuzz" to .01 won't
even join them. Or, if they are nearly perpendicular, and very close
to touching, the "extend" command won't work. We didn't have nearly
the polyline problems with 2002 that we have with 2004. I do know
that the problems are magnified when working on a drawing that was
originally created in LDT or ADT, and brought in to AutoCAD 2004.
Does a drawing created in LDT or ADT have the ability to permanently
change some fine settings when opened in CAD 2004?
Hope some kind soul will help with my questions! Thanks.