Same when using a clean Vanila or Entrenchment sins with the dev exe, you will have a few error show in the log... fact is that sins code is not bug free, that some model are not perfect ( mesh, uv, etc )... so minor error who don't crash the game can appear...
As today, no new software if not bug free at 100%... same thing for OS and driver... when sins was released, NVidia card was with problem but it was a Nvidia problem... Sins with Vista was with problem but it was a Vista problem... Sins have his share of problems but the majority of the big one was resolved in the last year...
The memory leak was reduced in recent engine build... but i am not sure that it is only a Sins problem... it can be a directx one too... with opengl, the leak appear in the graphic memory ( directx use main memory for cache the texture )... with opengl, it seem that the leak is more little ( it is why i think that the problem is not only sins related )... on windows system, you have no way to flush the leak... so, with time, stop and restart the game will become more difficult due to some memory fragmentation... only way if a reboot...