I’m a Blender virgin trying to edit some .OBJ (wavefront format) models.
I got as far as importing the .obj, but then I can’t seem to switch into Edit mode.
I also tried the following simple test to recreate the problem I’m seeing:
If I create a new scene, add a cube, then I can edit it.
If I export the cube as .obj, clear the scene, and then import the obj, I can no longer switch into edit mode.
What am I missing? I know this must be something basic, but every tutorial, wiki, document I check seems to imply TAB just works for switching mode. But all I see is Object Mode.
Cheers
Peter
Latest leopard on intel MacBookPro
downloaded version: blender-2.46-OSX-10.4-py2.3-intel.zip
Just right click on the imported object and then press tab. I know it looks selected after importing, but it is not.
wonderful 
Is there a difference between using ‘a’ for select all, and right clicking? Because I’d tried just about everything on the Select menu. Anyway big thanks for the fast feedback!
“A” will select everything in your 3D display if you are in object mode. However, Tab will only work with the single object that is the Active selected object. When you import an OBJ it is selected, but not the active selected object (why that is I don’t know). Right clicking makes the object the Active selected object.
To see the difference, start a scene and add two cubes as separate objects, right click on one of them and then Shift + right click on the other. The first cube will still be selected, but so will the second. The second cube will be the active object. The Pink outline for the active object is lighter (brighter) than the other selected object(s). This means that in Object mode, you can move both at once. However, if you press Tab only the second (active) cube will go to edit mode.
Now, I have just used the word active like 100 times, and I think I have confused myself. If the preceding is not helpful to you, just let me know and I will try to explain it better. LOL
very helpful and the detailed response is really appreciated!