Hi Need help as stuck with trying to restore OS to factory settings even using recovery disk

Hi,

Am trying to restore my OS to factory settings using the recovery Disc package I obtained from Acer. The following is contained in the package.

1 System Disk

4 Recovery disks

2 Language Disks

Followed the guideline provided by the Acer to carry out the operation. All goes well till the last recovery disc is inserted. System stops the process and throws up the message

" Restore Failed Error Code=0x241 (WIMApplyImage cannot apply image : Windows Cannot verify the digital signature for this file. A recent hardware or software change mighthave installed a file that is signed incorrectly or damaged or that might be..."