I have a Verbatim 320 GB 2.5" USB portable Hard drive. I have a strange problem with it. When I plug in the USB cord to my laptop (runniing Windows XP SP1), the blue light starts blinking and the hard drivr is not detected. Sometimes it works (steady blue light and disk is recognised) after I replug the USB cord 10/20 times. Please let me know if there is any solution for this problem

Hmm try to install a 2.0 driver into the laptop..to work at it best and to be seen this drive works on a 2.0 usb port ..it may be seen at one point in a 1.0 slot ..but it s just a gamble...so install a 2.0 usb driver ...and after that locate the usb port that sees it every time from first plug...
there is a posibility that you already have this driver installed..so ..just try to change ports until you hit one that sees it every time ...if you have only 2 of them you do not have much choices but one of them should be the one..
another thing to do ..is to just add it and run the add new hardware wizard from the control panel...choose already added..and it will show the devices...highlight it from the list and proceed to install ..it will be easier to see it in the future .. But remember the main reason its the sp1..and the luck of the 2.0 driver ..
just google for a 2.0 usb driver for sp1...and there are available downloads on the net ..this is not a rare driver ..its common for all usb 2.0ports..just get one that fits the operatio system you use..
Anoter suggestion is to get to windows Xp sp2..and let it update to sp3..you will get rid of all security and devise recognition problems..