"Runonce.exe"

​What's "runonce.exe"? I'm getting a message that this file may be corrupt and that I should reinstall it. Earlier today the power went out while I was on the 'puter. ​​ Once it came back up, the 'puter came on but got stuck in scan disk mode. I restarted it and it came back up just fine, but when I tried to access the WWW everything froze up on me. Now I get this message. Any help most appreciated. ​​Obviously I have WWW access again. ​