Apostolos,
You may be perfectly correct about the value of the Event Viewer report but the OP says he has no problem now so why do a reinstall? So far as system health is concerned he did run SFC, check for malware and come up clean.
Systematic troubleshooting is never useless -- a negative reply saves a lot of time and money.
So far as I am concerned helping users includes using techniques that destroy their system -- especially since few have adequate backups -- only as a last resort. But then I've been doing this since the 1980's and worked in hitech R&D for decades before that.