NT Explorer Mystery IE

Here’s a good one….A user using WinNT 4.0 opens NT Explorer, clicks on the a: drive and IE opens instead inside the NT Explorer window? This happens sporadically. I looked in the winnt folder to see if the explorer.exe file was damaged and foundthat he was using another NT exporer file with a .scf extension??? So I changed his shortcut to point at the NT explorer.exe, why did he have two nt explorer files under his winnt folder….?? Any ideas on this mystery???