I have my suspicions about IBrowse2.3 and SFS. Here the cache can corrupt the filesystem, especially on faster systems. I'd advise anyone who uses IBrowse cache to run it from a non-SFS partition, or a special cache partition of its own so it can be quickly formatted. This 'bug' really needs to be investigated.
Once any SFS partition is corrupt, you must rescue the files and then format. There is no way to fix it. That's why the IB issue is so serious.