If PGP Desktop hangs during decryption (or encryption), I have found that sometimes a Windows system command probably stopped the process. When this occurs, the progress bar (% complete) won't change, and you also won't be able to resume or stop (sound familiar?). In this situation, all you need to do is "nudge" the wde engine to start again.
Thus, do the following in the command prompt using the PGP command line instructions:
-->Start-->All Programs-->Accessories-->right click on Command Prompt then select Run as Administrator
Once you are in the black command prompt window, type:
cd \Program Files (x86)\PGP Corporation\PGP Desktop\
Once you are in the PGP Desktop directory:
(if you were decrytping, then issue the command)
pgpwde --decrypt --passphrase "passphrase" --disk 0
(if you were encrytping, then issue the command)
pgpwde --encrypt --passphrase "passphrase" --disk 0
You should then get a response which reads as follows:
"Request sent to Start decrypt disk was successful" for decrypting or a similar message if encrypting but only with "encrypt" instead of "decrypt" in the response.
Then, you will notice in the windows PGP Desktop window that the process successfully resumed.