I uninstalled it completely, and then when trying to install beta 1 again, I get this:

Database error in vBulletin 4.2.0:

Invalid SQL:

INSERT INTO vbpackage
(productid, class)
VALUES
('pmattachments', 'PMAttachments');

MySQL Error : Duplicate entry 'PMAttachments' for key 'class'
Error Number : 1062
Request Date : Sunday, June 10th 2012 @ 05:31:57 AM
Error Date : Sunday, June 10th 2012 @ 05:31:58 AM
Script :
Referrer :
IP Address : ++++++++++
Username : ++++++++
Classname : vB_Database
MySQL Version : 5.1.63-cll

I know you said that there will be no support, but I am really stuck now. Thanks.

Thanks for your update ;)

i'm waiting about the final version because i NEED this hack !! thanks a lot !

I get same issue

Database error in vBulletin 4.2.0:

Invalid SQL:

INSERT INTO vbpackage
(productid, class)
VALUES
('pmattachments', 'PMAttachments');

MySQL Error : Duplicate entry 'PMAttachments' for key 'class'
Error Number : 1062
Request Date : Sunday, June 10th 2012 @ 05:31:57 AM
Error Date : Sunday, June 10th 2012 @ 05:31:58 AM
Script :
Referrer :
IP Address : ++++++++++
Username : ++++++++
Classname : vB_Database
MySQL Version : 5.5.24-cll

That was a bad idea, your database is now in an inconsistent state.
-> Reload the backup you made before uninstalling Beta 1.

Sorry. You mean I must completely take my entire forum to the backup?

I don't understand though. I followed your instructions on how to uninstall. Why must I now go back to a backup?

That would be the easiest way to get the DB to a consistent state again, yes.
Another option would be to manually fix the DB (by removing the package, contenttype and all PM attachments before installing Beta 2).

As stated in the Add-on information this is unsupported Beta Software, it does contain bugs - like the one in the installation code you discovered :)
Bugs that are being discovered will be fixed, but I do expect beta testers to deal with issues caused by bugs themselves.

to fix which database table have delete ?

Yeah well, making a product available to the public which can completely ruin their complete forum is not very professional. And not even having the decency to offer help when begged for help! (I even offered to pay!)

He has a point and so do you. Beta software shouldn't be installed on a live site unless you think it's definitely flawless. And even so, backups are essential. It was most likely put out here for others to help find bugs and such, thus improving the product as a whole.

I recommend next time, when you try beta software, run it on a test site first.

And also, the developer has stated quite a few times that this product isn't supported and he will ignore support requests.