No mention of Brand of Pen Drive so I would start there first.
Try
www.pendrive.com or
www.brand.com (subsitute the brand)
Also no mention of when the latest updates were done ,hmmm
Normally should auto recognise when plugged in
(should do anyway)
When you install usb drive,
and drive does not appear be present,
SOLUTION...............................................................
Assuming your using XP,
go to start
then my computer,
right click,manage,
disk management,
This will put you in the area where you can check the health and activitys of your hard drives,
If this drive was recognised in the port then it will be visable in this area,
here you can right click on the drive and update the individual drivers of each device that may have issues.
So go ahead right click and update the drivers,
click I have disk on the wizard prompt and let the wizard search for the correct drivers,
if it comes back saying please insert cd then let the wizard search the internet for the correct drivers.
If this does not fix the problem then a Factory Default Reinstall will fix this.
If the issue still remains after these steps its the motherboard replacement time.
BACK UP BEFORE FORMATTING.......
Expert
