Confirm that the folder structure under C:\Users\<user>\AppData\Roaming\OCLC\, c:\Program Files\OCLC\ and c:\Program Files(x86)\OCLC is not hidden and the user attempting to search has full write permissions on the folders and files in them. Usually, an administrator on the machine can do this inside Windows Explorer by right-mouse clicking on the OCLC folder, selecting Properties > General and setting the Read-only and Hidden attributes to unchecked.