On a Windows Vista-based client computer, the following event may be logged in the Application log:

Log Name: Application
Source: Microsoft-Windows-User Profiles Service
Date: Date
Event ID: 1530
Task Category: None
Level: Warning
Keywords: Classic
User: SYSTEM
Computer: ComputerName

Description:
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-1-5-21-3112862306-1016156048-4130204762-1000: Process 932 (\Device\HarddiskVolume1\Windows\System32\svchost.exe) has opened key \REGISTRY\USER\S-1-5-21-3112862306-1016156048-4130204762-1000