Changing the CD drive to a CDRW/DVD on a 600X

[need help]

Hey everybody.
I have a 600X laptop and a friend gave me a CDRW/DVD drive. However, it did not fit (the connector was slightly more to the right than needed), so I changed the caddy (the plastic around the actual drive) between my old CD drive and the new CDRW drive. the caddy fit perfectly.

After inserting the new CDRW drive the laptop turned on and worked fine. It recognized the CDRW and there were no problems. After, i tried to restart it just to make sure it actually does work - and it wouldn't work. It goes to an error screen before it loads windows and that's it.

If i remove the drive completely, it turns on fine and everything works.
I don't know which thinkpad model the CDRW was used in before.

so my question is - what is the problem? Is there a software issue, where my windows XP does not recognize the new drive (but it turned on once before), or is there some problem with incompatibility issue between my 600X and the CDRW?

and what could i do?

thanks.