Yes! Laptops, boxes of documents, briefcases and even ***briefs*** were constantly lost during the clinton administration. ;)
I will say, however, that some laptops and disks have also been lost and some found again since 2001 (but we know the latter is not GWB's fault).
Well laptops are everywhere now so it's somewhat understandable. People don't normally carry around classified laptops anyway but there is "sensitive" information as opposed to "confidential" or "secret".