Boot.Tidserv is a Trojan which effect the Master Boot Record (MBR) by disabling the ability to browse the computer files when logging in. same symptoms may occur when booting with external device like flash USB, CD or any other method.
Using the Norton Power Eraser tool (NPE) and Symantec Endpoint Recovery Tool CD is recommended by Symantec but may not clear the Trojan.
However, downloading the Symantec TDSS removal tool should solve the problem.
Cleaning the Trojan is not enough, as the files and folder might not be accessed after removal cause the Trojan already “done his work”.
A great tool named unhide.exe. This will fix the inaccessible folder and files.
Thanks To Shimi Bejerano for the update.