Related to the new Vista version (5.5d) is the new non-Vista version (5.5c). 5.5c does not have the Microsoft compatibility certificate for drivers, which caused an OS-level warning and do you want to continue? message to pop up in the middle of the install process on XP ... after 5.5d has already deleted every trace of the previous driver. No matter which way I responded I got a totally messed up install, the inability to access all my previous paper definitions, etc., and no tool tray icon.
An e-mail reporting the problem and requesting a link to the previous cut of the driver resulted in the usual incompetent baffle-gab and no joy, so I'm now limping along with the original and highly buggy driver from the CD.
If you are using a previous version of the 4000 driver on XP, I strongly suggest sticking with that. (And if anyone knows where I can get a copy of the previous driver, I'll be greatly grateful.)