ImpEx failure to connect, can't figure out
 

I have been trying unsuccessfully to complete an import using ImpEx and hope I can get some more knowledgeable advice here.

My situation is that the forum I have been helping manage got hacked earlier this month and various php files (and possibly the database itself as well) were corrupted to a degree that would have been difficult (i.e. expensive) to repair. We were dissatisfied with our hosting provider and after receiving expert advice, decided our easiest path forward was to restore the forum to a fresh installation on a new server and import the old database into it rather than attempting to restore our previous setup. We also preferred the format of vBulletin 3 over vB4, so decided to use the latest version of vBulletin 3.8 for our new iteration (previous version was 4.1.11).

So far we have successfully gotten a fresh install of vB 3.8.7 Patch Level 3 installed on our new server, but we have hit a wall trying to import the old database with ImpEx. There are two errors that we have received, most of the time when the "Import" button is hit, we get the following:

HTML Code:
ImpEx Database error

mysql error: Link-ID == false, connect failed

mysql error:

Date: Monday 29th 2012f October 2012 05:10:21 PM
Database: dtcom_*****
MySQL error:
Then from time to time we get this message instead:

HTML Code:
Unable to add cookies, header already sent.
File: /home/*****/public_html/impex/ImpExFunction.php
Line: 522
Here is what we have tried so far to resolve this:

• Uploaded the old database .sql file to the home directory of our new host and edited ImpExConfig.php to find the source on localhost -- got the same connection error message
• Tried accessing the source DB a different way, by providing the hostname info of the "old" server which still has the old database on it, allowing Remote MySQL access on that server (allowing both our local IP address and the IP of the new host where ImpEx is installed), and trying to get ImpEx to grab the data that way; same thing
• Tried the above, but changing the password for the DB user on the old host, in case no improvement
• Edited the "new" server's config.php file to alter the cookies prefix from "bb" to "vb", hoping this would resolve the issue with the second error message, no change. Found one piece of advice suggesting to change the cookie path for the new site, but it warned that this might prevent admincp login, is this true, and how can that problem be avoided if the path does need to be changed?
• Disabled "hooks" (addons) for vBulletin
• Checked and triple-checked all information in config.php and ImpExConfig.php, all is correct.

At this point I am out of ideas and hope to get some input on where to go from here. Could this be an issue with the database itself? Using phpMyAdmin on the old server, the "old" database still appears fully intact i.e. members, posts, PM's etc are all there as they should be so our hope is that even if the table structure is damaged somehow the main data should still be able to be imported. Is there an issue trying to import a vB4 DB into a vB3 installation?

Appreciate any advice.... TIA