PC won’t read any USB flash memory

Hi, I’ve been looking at a PC that won’t seem to read any USB memory stick. I’ve tried 3 different ones that all work ok on another identical model PC (NEC Powermate with XP pro).
Each time the PC recognises the USB stick & assigns it to drive letter E: but when I try to open E: I just get either ‘Please insert a disk in drive’ or ‘this drive is not formatted, format now?’. Then, if I choose to format I’m told that the drive can’t be formatted.
I’ve looked in the disk management and the drive is always recognised but marked as ‘unreadable’.
The USB ports seem to be working ok ortherwise as the attached printer works fine. Any ideas anyone?