I'm on my Vista system at the moment but I still use my XP PC on occasion, and I haven't noticed this in the 6 years or so that I have had it.
I can't offer any concrete reason, but the Desktop display, (the icons on the Desktop and the Taskbar), is created by explorer.exe, (it is always present as a Process in the Task Manager). If the whole Desktop display disappears then reappears a short while later, I would have suggested that explorer.exe had stopped working for a bit, then restarted, but if it is just the Taskbar, I would not have thought that was the issue.
I wonder... How many Quick Launch icons and System Tray icons, (near the clock), do you have? If you have a lot of either or both, then possibly the Taskbar has to reconfigure itself to fit them all in?
That's all I can suggest, but perhaps others will have a better idea.
I've been wanting to ask this question for years but never have. On my computer at work and my computer at home that runs Windows XP something that I assume is normal happens to the taskbar during startup. Even though this may be normal, I'm wondering if there is a hack or something to fix it.
When Windows XP loads, and the desktop and start/taskbar appears, everything looks like it's loaded, but then the taskbar will go away just for like 1 second and then come back, then thats when I know it's completed loaded.
Although it's a small detail, it's kind of annoying. It's like the taskbar hiccups.
I believe it happens on every Windows XP computer I've ever booted up, so I'm guessing it's normal and there isn't a solution, but if anyone knows what I'm talking about and has a solution, let me know!