Install XP SP3 and things will be better. Disk is too large for this old version of the OS.
By the way, why use an Internet browser (like Firefox or Internet Explorer) to browse a local machine? Most people would use My Computer or Windows Explorer.
There has been a few forums on here about external hard drives not appearing in explorer or my computer but showing up in device manager and I also have that problem. My WD My Book 250gb usb desktop externall hdd works with both my macbook pro and HP laptop, but my HP desktop running windows xp media center (original from 2002) has the problem as stated above. In order to check files, I open firefox and to use open file to explore the drive, I've used the utilities of western digital and reformatted and everything works fine on all comps except this one. What can be the problem?