I'd started a thread over in the Beta section on this same problem (which Leonardo objected to, referring me to the thread relating to delays in receiving the license emails). Jv16 advised in that latter thread that the problem was due primarily to quirks in the email servers which he was looking into changing.
Back to the invalid-license problem, for which this has now (hopefully) become the proper home.
What I'm getting is this sequence:
1) "Thank you" email containing link to download site;
2) What's downloaded at that site isn't the license, but an htm which when opened points to yet another download link.
3) That second link downloads the xbin, and that's when I run into that "invalid or corrupted" problem a number of others have reported, when I start PT again.
On the possibility that that unusual second second step is somehow involved, I've asked veera if she could try again, but this time send the xbin as an email atachment. I also sent a message to jv16 back when this started, but haven't as yet heard back from him.
Might I suggest the title of this topic be changed, since apparently the problem's not specific to iMac or to Win 7?