Icons disappear under KDE 2.2.1

Dear all, some time ago I installed SuSE 7.3 with KDE 2.2.1. The system works fine but from time to time and suddenly, all desktop icons either disappear or loose their functionality; I mean, I can't click on them to launch an application. Once I left the computer turned on after the icons went away and they where back and "clickable" after about 20-30 minutes. Any ideas about what could be happening?? Thanks in advance! Martin