BleepingComputer.com: Keyboard/Mouse not working after startup (sometimes doesn't happen)

Just after my start-up, either my mouse or my keyboard doesn't work. This does not happen after every startup. When it happens, I trying restarting the computer (desktop computer) and it sometimes works. This started happening 2/3 days ago. I don't know the reason. I would like to add this information to my post: MY COMPUTER WAS RESTARTING AGAIN AND AGAIN AND SO WE CALLED A COMPUTER TECHIE. HE SAID THERE WAS A PROBLEM WITH ONE OF THE RAMS. IT WAS 1.49 GB RAM WHEN THAT PROBLEM USED TO OCCUR (RESTARTING PROB). HE REMOVED A RAM IT IT IS 1.24 GB RAM NOW. I HAD THREE SEPARATE RAMS BEFORE AND NOW ONE IS REMOVED SO ITS TWO NOW.

Specifications as it appears in System Properties:

Microsoft Windows XP Professional Version 2002 Service Pack 2.

Intel®
Pentium® 4 CPU 3.06GHz
3.07 GHz, 1.24 GB of RAM
Physical Address Extension

I will be glad if someone can help.

I am still waiting for my first reply.

hmm have you checked if it happens in safe mode (pressing F8 on restart) or have you tried using a different mouse and keyboard

I have not checked whether it happens on safe mode or not. I have also not tried with a different keyboard or mouse.

btw it doesn't happen most of the times.

Does that Keyboard & Mouse using USB Connection?
And please check does it happen on safe mode or not?

@above

Can you please re-write in other words?

"Does that Keyboard & Mouse using USB Connection?"

couldn't understand that

Does your Keyboard is USB Keyboard?

Does your keyboard and mouse connected via USB port? If yes kindly check connect them to other ports or try to clean those ports maybe they are just dirty.

@above 2 posts

nope.......its just a normal keyboard and a normal ordinary mouse. It is not happening now but I want to know why it happened a few days back?