trouble mapping network drive in windows 7 pro x64 bits

I have my work network setup with ALL Windows 7 machines 5 years ago, and up until recently I have had no problems mapping network drives. Now, I'm having trouble mapping a network drive but only from my most recent computer added to my network. the settings are 100% identical to my other computers which I have successfully mapped the server drive for the last 5 years, but I can not map the sever drive and it tells me access denied you don't have permission for this . all computers are configured the exact same way all are running Windows 7 prof x64 bits. under my network in file explorer my server shows up .
I found some discussion about this but long ago. can anybody help please .

Thanks Paul , I installed that patch but it still does not allow me to map the network drive. still says "access denied" but all my other machines works perfectly with the same identical settings.
any other suggestion ?

cheers

Have you setup a share and then set NTFS permissions failing to set NTFS is the most common fault