Well I tried using Knoppix vga=normal at boot and that message "You passed an undefined mode no." didn't occur but monitor blinks fastly later.Actually when it was blinking I kept on pressing ctrl-alt-del and after sometime it returned to the dos window and there the following was written,
Starting single X-window session for user knoppix. Please stand by a few seconds while the optiman configuration is being determined.
After this system terminates, the system will automatically shut down.
Starting X11...[drm:drm_init]*Error* Cannot initialize the agpgart module
So this was there, I dont know whether the above was displayed before that blinking occured or during or after that blinking process.So please help what to do as I am struggling