Concurrent license lockout issue

At my community college, we use s/w called “English Mastery” which is wonderful but unsupported. We are having a problem with users being locked out of the software because all of our concurrent use licenses are supposedly “in use”. However, we know for a fact that this is not the case. For some reason, the “licenses” are not being released when they should be, or perhaps they are not all available in the first place! Rebooting workstations helps with this sometimes, but not always.

Our workstations run Windows XP with SP2, and our servers run Windows 2003 Server. TIA for any helpful hints.