Desktop Icons Disappears In Win 7
Links To Files May Suddenly Disappear From A User's Desktop On Windows 7
Users may find that some of their links to files inexplicably disappear from their desktop, without warning.
Windows 7 has a new Maintenance feature which, amongst other things, proactively removes broken links. This is an enhancement to XP's often disabled "you have unused icons on your desktop" feature.
This continues Microsoft's philosophy of keeping the User's desktop as uncluttered as possible, but marks a more aggressive turn to clean up.
The service is set to run once a week at 1AM every Sunday. However, if the computer is not on at that time, it will re-run whenever the system turns on.
Problems can arise if the computer shuts down the network when it goes into sleep mode. This may cause shortcuts to mapped drives or file to appear broken when in fact they are not.
The KB article from Microsoft: http://support.microsoft.com/kb/978980 explains how to turn off this feature. But following their directions turns off ALL the maintenance that Windows 7 typically performs. So there is no way to stop it from cleaning up your desktop for you without affecting other things.
Under Start | Accessories | System Tools | Task Scheduler, if you expand Microsoft>Windows>Diagnosis you can disable the task which runs the maintenance. But this has a similar affect to following Microsoft's suggestion.