try doing this it may get those trouble some pens working.
click this link and download the windows 98se driver.
http://www.sandisk.com/Retail/Default.aspx?CatID=1093
do not use the self install.
unpack the driver with winzip in to a folder on your desktop.
now plug your pen in, if windows starts to moan about a driver and starts the wizard choose don't search i want to choose what driver to install.
now browse to that folder you just unpacked that driver in to and click next if your lucky windows will use the 98se driver.