I just read somewhere about formatting /data before an install and when I tried to do that I received: "error formatting /data".
Googling that error I found a thread on xda where I guy had the same problems as me and it sounds like he wasn't able to fix it:
"error formatting /data" and "error formatting /cache" - xda-developers. something about a filesystem error.
What do you think? Is this the end of the road?