Can I cancel drive decryption?

Hello,

After receiving BSODs and being unable to fix boot sector, I ran drive decryption with PGP's decryption CD, and is taking 3 days and counting. I bought a carry case to plug de hdd to another PC through USB, in an effort to reduce decryption time. But my question is: can I safely shutdown the decryption process, and resume it, after pluging it through USB to another PC?

Thanks