Reproducing problem:
-Select an object (preferably with more than 30 vertices, otherwise effect will not be obvious)
-Go into edit mode and deselect all vertices
-Make sure you are in 'Draw type: Solid' mode, vertice select mode, and 'limit selection to visible' is enabled
-Press 'Border Select' key (B) twice and click to select any number of vertices

Occasionally, for no apparent reason, border select in Blender 240 through 243 selects a random set of vertices - It selects vertices, but from all over the model, and only some are within the area of the border selected.

This happens on the following four systems:
System A:
- Blender 243 (Although this problem happens on Blender 240 to 243)
- Windows XP Home Edition (SP2)
- NVidia 6600 GT
- Python 2.4
- 768 MB RAM
- 3.2 GHz Intel Pentium 4 (HT)
- Logged in as Administrator

System B (Yes, this is a different system, despite the specs):
- Blender 243 (Although this problem happens on Blender 242 to 243 on this system)
- Windows XP Home Edition (SP2)
- NVidia 6600 GT
- Python 2.2
- 768 MB RAM
- 3.2 GHz Intel Pentium 4 (HT)
- Logged in as Administrator

System C:
- Blender 242a (Although this problem happens on Blender 240 to 242a)
- Windows XP Home Edition (SP2)
- ATI Radeon 9550 SE
- Python NOT installed
- 256 MB RAM
- 1.8 GHz Intel Celeron
- Logged in as Administrator

System D - Workstation Client:
- Blender 243 (Not encountered with any other version, tested with 240, 242, 243)
- Windows XP Professional (SP2), with Novell Netware 5
- Internal Graphics Adapter/Unknown Graphics Processor
- Python Installation Unknown
- >256 MB Ram (Amount unknown)
- Intel Core 2 Duo (Speed Unknown)
- Logged in as Power User




Beyond using Border Select, no other events appear to lead up to this problem within Blender itself, however I do not know how external events lead up to this problem

It does not appear to happen with an installation of
- Blender 240
- Full installation of Red Hat 9, KDE Interface
- Radeon 9550 SE
- Python Installation Unknown
- 256 MB Ram
- 1.8 GHz Intel Celeron
- Logged in as a standard user

although this has not been tested properly.

The problem is very rare on System C and D, but quite common on System A and B (happens, on average, every 10th/20th run of Blender, though not every 10th/20th consecutive run - occasionally it happens four or five times in one day, others it runs fine for a week)

I cannot recall, unfortunately, whether I rebooted the computer, or just restarted Blender to fix the problem.