VBO Limits?

I have a terrain engine which uses VBO’s, the code for the VBO’s seems pretty solid, its abstracted away into a server kind of interface. Anyway, my terrain works flawlessly for anything less than and including 512x512 terrain. But when i load say a 1024x1024 heightmap, it lods the terrain, and then, first error is it doesnt draw the texture, the terrain is just plain white, also, after around 5 seconds, the program crashes and in video studio it says that the error occured for glBindBuffer
Oh yeah, im storing the entire vertex data in 1 VBO. So yeah, is there some kind of limit on how much data can be stored in a single buffer? Do I have to break it up into multiple buffers or am I plainly doing something wrong and should go back to debugging?

Oh yeah, im on WinXP, AXP 2800 512 MB Ram with a GFX5900 128MB RAM
Thanks in advance.

depending on how large your buffer is for 1024x1024 it might well be the problem. just call glError after glBufferData and see if something went wrong.