trouble with taskbar icons

I have a problem that I have never seen addressed anywhere. Whenever I reboot my machine, the taskbar items in the bottom left never load the same. Sometimes the icon loads, other times it doesn't. Happens with all programs that I have set to always show. I am running WinXP sp3, a 3 ghz processer with 2.5g of RAM. The programs that don't show up ARE running but without the icon makes it difficult sometimes to do anything with the program (like the volume control, safely remove hardware to name a few. Any suggestions?