MXTASK is likely a holdover from a partially removed System Suite or Fix-It Tools AntiVirus loader. It will be listed in MSCONFIG under Services as "SystemSuite Task Manager" or "Fix-It Utilities Task Manager," with Manufacturer name of V Communications, Inc. (or if it's an old installation, OnTrack Data International).
Still a good idea to scan for viruses & spyware; this just isn't a reason.
Sloth is the mother of invention. Necessity is just a mother...