recently moved encrypted files to external hard drive and exported backup certificate for the files. I installed new hard drive and reinstalled Windows 7. I copied over the encrypted files, installed the certificate successfully in the personal folder. The certificate said it would not be trusted until I installed it in the trusted root directory. I installed it successfully there as well. when I try to open an encrypted file, it returns 'The file you are trying to open, '*.xls' is in a different format than specified by the file extension. verify that the file is not corrupted or from a trusted source before opening the file. Do you wish to open now?' When I click yes, the file is unreadable. I am unable to open any documents in the encrypted folder. I am not too familiar with certificates so if anyone has any suggestions, please advise. Thank You.