System Information
Linux bubastis 3.10.25-gentoo #10 SMP Thu Jan 30 22:17:35 UTC 2014 x86_64 Intel(R) Core(TM) i7-4800MQ CPU @ 2.70GHz GenuineIntel GNU/Linux
01:00.0 VGA compatible controller: NVIDIA Corporation GK107GLM [Quadro K1100M] (rev a1) (prog-if 00 [VGA controller])

Blender Version
Broken: git 08bf531956b1c1cff3319d119e8aba55b7a09b9e
Worked: 2.70-linux-glibc211-x86_64

Some time after 2.70 was released a regression was introduced which prevents PgUp and PgDn from moving NLA tracks. Moving NLA action strips still works.

To reproduce this

• put a keyframe on the default cube (location is an easy choice),
• use the vv button on the right of the track name in the NLA editor to create an action strip.
• use the Add > Add Tracks menu option to add a few more tracks.
• move your mouse into the track name section of the NLA editor and select one of the tracks. Attempt to relocate the track using PgUp and PgDn. It does not work.
• move your mouse into the action strip section of the NLA editor and select the recently-created action strip. Attempt to relocate the action strip using PgUp and PgDn. It works.