Everytime i do a system verification in disk utility the volume count is wrong. I know how to fix it as i ve asked it in this forum before. But as it come back some ppl advised me to install OSX from the scretch and format the disk before. Where can i find the steps to fallow? I have an macbook air therefore osx on USB stick I have backup with time machine every week so can i use these backups after or does it bring the problem back ?