I have a drive on my Win7 Pro 64-bit workstation that is mapped to a SharePoint 2010 folder (I am connected to the company LAN by VPN). When I click the drive link I am prompted for my SharePoint credentials. When I supply them they are rejected (the prompt dialog pops back up) and my account gets locked out immediately - on the first try (elsewhere we have 3 tries before being locked out). Our tech support is investigating, but after several days they have not found the cause. I have no problem accessing the same folder by browser - my credentials are accepted and I can go right in.