This crack is for Popupcop version 1.1.0.8 only.

Put popcrk.exe in the folde (directory) that popupcop.dll
resides in eg .. (root):\program Files\Popupcop

Make sure IExplorer is NOT running
Run popcrk.exe

Run Iexplorer
Select Register PopupCop

The Username must be at least 5 chars
The RegCode (password) must be 15 chars no more no less
eg.
Name   : Hello
RegCode: 123456789054321 << 15 chars

it can be anything have fun.