Cubase 5 issue

Hello! I use Cubase 5 and it worked perfect until I bought a much powerful PC and installed Windows 7 x64 (I had XP SP2 on the previous PC, if I remember well). Now, the recorded vocals sound awful, so much hiss on background and it sounds like the input sound level of the microphone is set to 100dB or something like that (clipping at its best). I used the same software/hardware settings back when I had the other PC (on XP) and I didn’t have problems. Also, with the same settings, Cubase 6 works perfect, but I really want to make this one to work. I tried to run the program in compatibility mode but nothing changes. I have an Audio Technica AT2020 cardioid condenser microphone & Yamaha Audiogram 3 USB audio interface. Any ideas ?

What version and build of Cubase 5 do you have installed (Help, About)? Are you using any plugins in the project?

v5.1.0 Build 105
I use some VSTs from iZotope for master process only (of course, and the basic ones from Cubase).

Ok, if I switch to ASIO4ALL v2, everything looks fine. But still, on Asio DirectX Full Duplex driver it’s a mess, as I said (using Cubase 5, Cubase 6 works fine with that driver tho.).

I would suggest updating to 5.5.0, then 5.5.3 from http://www.steinberg.net/index.php?id=downloads_cubase_5&L=1

I would normally expect you to set the ASIO driver to the Yamaha. I would recommend installing the latest driver from http://download.yamaha.com/search/product/?site=usa.yamaha.com&language=en&category_id1=16244&category_id2=16268&category_id3=&product_id=775002 Then shut down, restart the computer, and then select the ASIO driver for the Yamaha.