Kai:
Dec 9 04:30:35 nx10 kernel: EXT3-fs error (device hda3): htree_dirblock_to_tree: bad entry in directory #1330023: rec_len % 4 != 0 - offset=10264, inode=808542775, rec_len=13621, name_len=100 Dec 9 04:30:35 nx10 kernel: Aborting journal on device hda3. Dec 9 04:30:35 nx10 kernel: ext3_abort called. Dec 9 04:30:35 nx10 kernel: EXT3-fs error (device hda3): ext3_journal_start_sb: Detected aborted journal Dec 9 04:30:35 nx10 kernel: Remounting filesystem read-only
Updating to 4.5 was just a coincidence. I believe you have a disk that's going bad. I've seen this error three times and it has always been a bad disk. Backup what you can and replace the disk.
Alfred