I have seen that problem, for years (I think I logged a problem, that got closed as "not reproducable"). I have no idea what causes it. Sometimes it happens shortly after boot, and sometimes it runs for weeks before it happens. Usually, a WPS restart will "fix" the problem, for a little while, but a reboot is needed to get more than about 30 minutes until it happens again. It definitely has nothing to do with the new XWP, but it could be caused by an old bug in XWP.
Changing "SET SHELLHANDLESINC=" to 90, in CONFIG.SYS, seems to help, but it still happens sometimes (I haven't tried more than 90).
I will note, that I never saw it when I was using the XWP Turbo Folders feature, but that may have been coincidence. I don't use (or like) XView, but that is a personal preference.