1. Check client on site via "repair" button. 2. Check client with check4game utility. If it not help, run process diagnostic with check4game. Run utility as Administrator, start process diagnostic, wait for it, paste full result in thread without any truncation.
Seems like your HDD is almost dead. Download this app https://osdn.net/projects/crystaldiskinfo/downloads/65980/CrystalDiskInfo7_0_4.zip/ and make screen of full info window