Redirected printer ports filling up registry

We have a situation where redirected printer ports (using universal printing) are filling up in a users's registry in here HKCU\Software\Microsoft\WindowsNT\CurrentVersion\Devices

Once the number of ports reaches 100 (ports can be numbered from 00-99) the user starts getting this error in Office programs "Windows cannot print due to a problem with the current printer setup"

What we've noticed is that the printer ports used by vWorspace are named Ne01, Ne02 etc which appear to be network ports. These don't get removed when the user logs out unlike RDP redirected ports which are named TS01, TS02 etc. So eventually each user hits this limit and gets the aforementioned error, after which we need to manually clear out the unwanted registry entries. What's really odd is that the ports listed in the registry show all ports for all users with redirected printers on that server, not just ports for the user with the error. The upshot of this is that the above error can occur for users who don't even have universal printing enabled.

So, how do we stop this happening?

Thanks.