Hi Rabin.

Blender 2.5 needs more memory and a newer graphics drivers than 2.4 does.
You have to tell us what gfx card type you have, and check on possible driver updates for it.

XP is quite old now though... not sure if updates for this exist.
(moved to opengl tracker)

Moved from Blender 2.5 Bug Tracker to OpenGL errors

I tried it on another PC with xp with 128MB RAm and its working fine too.

I think it was because of Python i have installed for 2.49. I think 2.56 had python in its self so 2 python is making it crash .
could it be?

Check the terminal that opens when you start blender for prints?
I don't think it's python though, but you never know.

I am not understanding you what "the terminal that opens when you start blender for prints" means?

If you start blender, it first opens a terminal. A "DOS box" or whats it called... here is where error prints are shown.

its blank, totally black.

Strange... it should at least print some python stuff... but it's well possible the graphics card/drivers can't handle requests from blender and hang.
Nothing we can do really... this requires a coder with a similar system to dive into it, and yours is so old that it's not much likely to happen.

BTW:

- blender.exe should be in the same directory as the installation, to find all dlls and stuff
- open a Windows Command (cmd.exe) cd to to the install dir, and run "blender.exe -d"

That should give many prints

It worked after Formatting and installing Xp back. May be my old Xp installation had some problem or file mission. Now Blender is running well. Thanks for answering back.