If you get the following error:
Source: EDI Subsystem
Category: BizTalk Server 2006
Error encountered: ERROR (120) :
An error occurred in the File System connector. Check the details.
Cant make a connection to   \\MyComputer\EDIDocsHome\Documents\PickupEDI
Error message: The operation cannot be performed because a network component is not started or because a specified name cannot be used.

Check the Security Setting for the file share "\\MyComputer\EDIDocsHome\Documents\PickupEDI"

Make sure "EDI Subsystem Users" group has Full Control to the share.

By default, it is located @ C:\Documents and Settings\All Users\Application Data\Microsoft\BizTalk Server 2006\EDI\SubSystem