Readynas NV+ hard drive issues

Hi

I have a readynas Nv+ with 4 x 1tb hard drives installed.

About a week ago the system sent me an email about a disk failure on disk 3. Not thinking much of it, I ordered a replacement disc online. I was unable to find any similar seagate hard drives to match exactly the one (ST31000340NS) that went down. Thinking to the future I ordered a 2tb seagate drive off the hardware compatibility list (Seagate Barracuda ST2000DM001). It arrived and I popped it in, it found the disk and started an initialisation process (and sent me an email) , a few hours later I received another email saying that initialisation was complete and a raid sync had started. This is where it starts to go wrong. Sometime after this starts the system seems to crash , no access through a web browser and it doesn't show up on raidar. The only was I can get access back to the system is to take out the power supply. The first time I did this I left the hard drive inside and the above process started again, only to crash again on the resync.

I then found online a seagate ST31000340NS 1tb drive so ordered one thinking(hoping) it was an issue with using the 2tb drive. Unfortunately I inserted the 1tb drive tonight and the system hung again.

I'm using radiator 4.1.13

Has anyone got any thoughts? I can upload logs I have downloaded but I'm not sure which one will be of help?

Thanks in advance for any help

Matt