Explorer bombs out

When attempting to access a network folder or file, Explorer simply closes (disappears) and eventually drops you back to your desktop. The error in Event Viewer reads:

Faulting application explorer.exe, version 6.0.2800.1221, faulting module ntdll.dll, version 5.1.2600.1217, fault address 0x000080db.

What causes it and how do I rectify the problem? Keep in mind that the latest updates, including SP’s, have all been applied prior to this development.