Originally Posted by Paul M

Unfortunately you have fallen victim to impatience and a lack of feedback from the product install system. The installation includes creating two indexes, which on larger forums can take a bit of time (and as you noticed, drive the server load up while they are created). vB just shows a blank screen while this creation takes place.

Because you stopped the install mid process, the product id exists, which is why you get the duplicate problem. On the import, try setting the "allow overwrite" to yes. Install it at a quiet period and just leave it to proceed, blank sccreen and all.