I don't see mention of if you when the next step, that is use the mtrbd. install disc provided and do after the new OS install. That has to be done and again, refer to the 64-bit side of it all. if not part of the provided disc, then visit the mtrbd. website and get whatever is missing or related to 64-bit installs. On top of that, newer released installs, etc., could well be available and use those on top of anything already installed. Use common sense and get the required updates, etc.. also would discount any "bios updates" here too. At least check the status, if you at bios xxx-2 and now xxx-4 is available, it usually good to install, but that is something left to you to decide. of course, if nothing seems to correct the problem, that maybe an area to look into regardless.
I assume also that the HD was wiped and/or formatted as well. AQlso, consider that older 32-bit pgms. if installed are looked at for any improvements or requirements that 64-bit may impose on them if any. In this area it maybe far better to get the newer s/w version rather than trying to maintain older releases, even if you have to pay for it maybe at reduced cost, etc.. yet another area to check into.
However, if you problems quickly even before any pgms. or such are installed, look squarely at the 1st paragraph I supplied. It's important to review what's what. You may want to check the device mgr. area and see if anything is red/yellow flagged in the listing or anything is out of place, as the whole listing should be collapsed. I hope this all helps...