Run away task

We have a NT 4.0 server running Informix Dynamic server 7.30.tc2, on a 300 MHz Pentium II. Every now and then the computer runs real slow, analogous to a 486 or worse. (I know NT will do that to a system). When we investigate there is a task that has been submitted by the engine that contains the following SQL: select nextns, nptotal, npused from sysptuhdr where partnum = ? When we kill this session the computers response time returns to normal. This has occurred on both Dynamic server and Workgroup Server. When we called Informix Tech support, after we convinced the tech we really couldn't run ps - ef, she told us that her documentation says that we should not touch that table. We agree and as far as we know are not, the engine has started this session. Does someone have an idea what this is doing and how can we keep it from monopolizing the server processor? Thanks Shannon