Alright then,
When the popup in the corner of the screen comes up, it should say:

"Found New Hardware:
PSP Type A"

and then

"Found New Hardware:
Your new hardware is installed and ready to use."

Now, if you've been using that computer with your PSP before, a New Hardware message shouldn't have even come up. Are you sure that this is the exact same configuration as previous times? Try wiggling the cord a bit from each end just to be sure.