The system froze when I was sending an SMS via bluetooth from address book, and I had to do a forced restart. When it did restart, a blue screen appeared with a cursor. I don't have the system DVD with me that came with the machine, so after looking on the net, I entered into single user mode, and ran fsck. This told me that I had an overlapped extent allocation, and gave a number. When I searched for the corresponding file, it was bn.dat, a couple of folders deep within syncservice in the application support folder. Any ideas? Can I just delete this file? I've heard that DiskWarrior is probably the only way to go.