In Windows Explorer, select Tools | Folder Options in the menu. Select the View tab. Click Reset All Folders. Reboot.
If that doesn't work, in Windows Explorer, select Tools | Folder Options in the menu. Select the View tab. Clear the "Restore previous folder windows at logon" setting in the Advanced Settings list box. Reboot. You can re-enable the setting if you'd like.
If neither of those worked, then it's most likely not a problem with Windows Explorer, and there really is something causing the window to open (e.g. by running explorer.exe "C:\Program Files\VIA"). A quick way to test this is to hold down the Shift key after logging in (keep holding it down until after Windows Explorer initializes the Desktop). That prevents most, but not all, startup-like objects from being parsed.
Trev