so after i posted here to get the users' feedback, i tried again to repair the laptop. i thought it might be a software problem. i called ibm once again, and posted on experts-exchange.com. there was no help in either place. so i bought a USB 2.0 PC Card, but i didn't like the mess the extra equipment caused, especially that i knew that my laptop had this functionality built-in. also, the USB PC Card wasn't good at providing power along with data from the USB port. it was only good for data.
so i took my laptop to a nearby authorized repair center. they said that updating the BIOS should solve the problem. i thought i had the most updated version, but i was wrong. so they updated the BIOS, but as i expected that didn't fix anything. all this was a few weeks back.
few days ago, i called the authorized repair center again and told them that updating the BIOS didn't help. so they ordered a new motherboard, and called me when it arrived. i took my laptop to them yesterday, and received it today. USB is functioning perfectly now.
i guess the story ended happily. oh, and btw, my laptop is still in-warranty






