Test platform Win2000 SP4.
1. Bug: Drive bar buttons don't always sync with panel contents. Sometimes for example the D: button will be shadowed but the contents of C: are visible in the pane.
I'd prefer the original drive-selector dropdown anyway, but I can't find any way to get back to it. The new drivebar gives no path information, whereas the old one did.
2. NTFS Encryption options:
Most users have zero understanding of Microsoft's rather unconventional encryption-scheme, and will fall straight into the trap of assuming that all they need to decrypt the files is their password. By the time they figure-out that's not the case

Not strictly a bug, but if 2.5 is to be rolled-out into an office, I for one would need a way to remove the Encryption menu items. I think most sysadmins would agree on this.