Outlook 2007 email stuck on task bar

Hi all, I have been having this ridiculous problem at work. I'll open a new email then I'll close it, but on my windows XP task bar it's still there. It doesn't show up in task manager. I can right click it and hit close, but nothing happens. Same with restore and any other choice I have.

I found a few other threads like this around at various sites, but none have answers. I just figured I'd see if anyone has any ideas. It's not that big of a deal I can get rid of it by closing Outlook, but it's just a hasle having to re open it every hour or so.

Open Task Manager, Click the Processes tab, right-click and end all instances of OUTLOOK.exe. After doing that hover the cursor over your Outlook tray icon and it should disappear.

I can just close outlook normally and it will go away. I'm wondering if there's a way I can stop it from happening at all though.