Broken line if using glTranslate - opengl

Question

I'm trying to draw a line strip on an opengl project.
If I use the glTranslatef function to the transformation matrix, the magenta line strip is drawn broken as show in the figure:
And moving the view, the line strip is broken in different points, or drawn correctly, or not drawn at all.
If I translate manually the points, the line strip is always displayed correctly.
The other lines (red ones: GL_LINE_LOOP, cyan ones: GL_LINES) are manually translated and work properly.
Here is the code with glTranslate:
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glTranslatef( offs_x, offs_y, 0);
glLineWidth(2.0f);
glColor3f(1.0f, 0.0f, 1.0f);
glVertexPointer( 3, GL_FLOAT, 0, trailPoints );
glDrawArrays(GL_LINE_STRIP,0,numTrailPoints);
glPopMatrix();
and here the working code with manual translation:
for (i=0; i< numTrailPoints; i++)
{
translatedTrailPoints[i].x = trailPoints[i].x + offs_x;
translatedTrailPoints[i].y = trailPoints[i].y + offs_y;
translatedTrailPoints[i].z = trailPoints[i].z;
}
glLineWidth(2.0f);
glColor3f(1.0f, 0.0f, 1.0f);
glVertexPointer( 3, GL_FLOAT, 0, translatedTrailPoints);
glDrawArrays(GL_LINE_STRIP,0,numTrailPoints);
What I am missing here?
EDIT :
To complete the question, here are the data structures (in inverted declaration order for better readability):
vec3 translatedTrailPoints[C_MAX_NUM_OF_TRAIL_POINTS];
vec3 trailPoints[C_MAX_NUM_OF_TRAIL_POINTS];
typedef union
{
float array[3];
struct { float x,y,z; };
struct { float r,g,b; };
struct { float s,t,p; };
struct { vec2 xy; float zz; };
struct { vec2 rg; float bb; };
struct { vec2 st; float pp; };
struct { float xx; vec2 yz; };
struct { float rr; vec2 gb; };
struct { float ss; vec2 tp; };
struct { float theta, phi, radius; };
struct { float width, height, depth; };
struct { float longitude, latitude, altitude; };
struct { float pitch, yaw, roll; };
} vec3;
typedef union
{
float array[2];
struct { float x,y; };
struct { float s,t; };
} vec2;
I'd like to second datenwolf's suggestion, but with no success: I tried pragma pack(1 | 2 | 4) before vec2 and vec3 declaration, I tried compiling with /Zp1 | /Zp2 | /Zp4 (I'm under VisualStudio 2008) but the broken line/points still persists.
EDIT2 :
Same problems with textured quads:
vec3 point;
point.x = lon;
point.y = lat;
point.z = 500;
glTranslatef( offs_x, offs_y, 0);
glBindTexture(GL_TEXTURE_2D, iconTextures[0]);
glBegin(GL_QUADS);
glTexCoord2f(0.0f, 0.0f); glVertex3f(point.x-C_ICON_WORLD_SIZE, point.y-C_ICON_WORLD_SIZE, point.z);
glTexCoord2f(1.0f, 0.0f); glVertex3f(point.x+C_ICON_WORLD_SIZE, point.y-C_ICON_WORLD_SIZE, point.z);
glTexCoord2f(1.0f, 1.0f); glVertex3f(point.x+C_ICON_WORLD_SIZE, point.y+C_ICON_WORLD_SIZE, point.z);
glTexCoord2f(0.0f, 1.0f); glVertex3f(point.x-C_ICON_WORLD_SIZE, point.y+C_ICON_WORLD_SIZE, point.z);
glEnd();
Results changing the view:
Correct drawn
Bad 1
Bad 2
EDIT3 :
I was able to correct the textured quads case by translating by (point.x + offs_x, point.y + offs_y, point.z) and removing the point coordinates in the glVertex definitions. The behaviour in the previous mode still puzzles me.

Answer 1

Try using glLoadIdentity() between the glPushMatrix() and glPopMatrix() calls since it resets the coordinate system and applies the translation for a fresh matrix.