when i boot the option appears (black screen not blue)--boot from cdress any button(and cursor keeps blinking) if i don't press any button then xp is booted normally.
problem is that everytime i switch on my computer it consumes lot of time.
also screen which appears shows ram ddr rows,cdrw type etc.........

so if you know how to disable this black screen please help! ;D

It is all about BIOS, first of all in BIOS set first boot device as HDD, also in some bios there is option to QUICK boot and sometimes Silent Boot.
Enable whichever.

please explain how to open bios and change settings?????

If you remember a while back I wrote an article, this is from that article :

. Optimizing Bios
BIOS stands for Basic Input / Output System, it is bios which first boot your system and then handle control of your computer to operating system. In bios, usually two things you can do to boot computer little faster and actually it impacts a lot.

* Setting right boot device order:

This is most common misconfiguration in computers if you never touched your bios, actually it is set to boot from Floppy driver or from CDROM / DVD drive and then only after if both above fails, then it looks for your hard drive for boot records. So wasting a lot of seconds.
So how to enter into BIOS and what to modify?
When you press computer then usually you can enter BIOS by pressing F2 key, in many system it is done by DEL key. So when you enter you bios, look for boot device order or BOOT option and their set your Hard drive to look first for boot record.
I am not going in details how to do it step by step as there are some variation but looking into BIOS carefully, you can easily find out.

* Enabling Quick Boot:

While system boots, BIOS go through some basic test which you can actually skip to boot it faster. Many bios do not have this feature and many does. My earlier computer had this feature ie. Enable Quick Boot but the one now I am using is without this. It will not give a boost to boot but yes, you will have marginal improvement.

Link to article:
How to quick boot/ boot faster

thanks i'll yry it out.

it worked great.
there were many options in bios so if you get time please explain all of them and their advantages.

I am glad it worked for you.
As you said there are many option in bios and they differ system to system slightly.

You may ask about anyone you want to know, if I know about it I will explain. Better use separate thread for each option.

ok i'll ask about each of them seprately in software section.