If it was a "Watchdog Violation" I believe those are caused by issues with drivers, and often SSD's. I'm not sure whether this will help since you said it was working fine before but I would try and update the firmware for your SSD (if you have one) and see if that helps. Since your wireless speed has dropped maybe also try updating your wireless drivers? I know you said you have already updated drivers but maybe you forget them.
If not then maybe a virus scan? Just as a precaution to make sure that it's nothing malware related.