I have avast free and I get this warning in the Event viewer and it saids Windows detected your registry file is still in use by other applications or services. The file will be unloaded now. The applications or services that hold your registry file may not function properly afterwards.
DETAIL -
1 user registry handles leaked from \Registry\User\S-1-5-21-3576144554-1218276841-3395113912-1000:
Process 1300 (\Device\HarddiskVolume3\Program Files\AVAST Software\Avast\AvastSvc.exe) has opened key \REGISTRY\USER\S-1-5-21-3576144554-1218276841-3395113912-1000