Windows 7: disappearing mapped drive shortcuts on desktop

Not sure when or why it happens but about 5 shortcuts I have on the desktop to mapped drives\folders will disappear. Everything else is fine. X64 7264.
Any ideas?

They disappear or become greyed out/ not showing the icon?

If they're just greyed out then the desktop needs to refresh.

Completely gone

Right click on desktop, choose "Personalize". On the left hand side choose "Change desktop icons".

I always make sure "User's files" is checked. Maybe you should experiment with the "Allow themes to change desktop icons" option. It's near the bottom.

Edit: I assume you have "Show desktop icons" enabled? Right click on desktop. Maybe some tweaked setting changed it.

Did these drives become disconnected at some point while logged in? I have noticed that desktop short cuts act differently than folder shortcuts.

Users files is just the Windows 7 'my documents' equivalent. Allow themes is checked.

Pretty sure the mapped machine was running fine the whole time it did it today but tomorrow I'll do an experiment and see if it effects it.

got a chance to reboot the other one and it had no effect on my shortcuts. hit refresh a couple times, tried to open one while it was gone. it asked me if I wanted to delete the one I was opening but that was it.

That is very odd. Hmm... Was this an upgrade? Were these drives mapped prior if so? Also, when they do dissappear from the desktop, are they still mapped in the "Computer" section?

The mapped drive still shows up in file explorer and shortcuts located in folders on the desktop are all still there, just the ones on the desktop get deleted (not in recycle bin either). It was a clean install. This has happened about 3 times to me. The computer I'm mapped to is running XP btw, not that that should matter.