When trying to apply an update to Service Accent, or if Service Accent is auto-updating, you may receive notifications that the update process could not install files locally.
Windows Vista's User Account Control is a setting (enabled by default) to prevent rogue applications from performing malicious operations. Such operations include copying exectuable/Activex files to the local drive, which is what the Service Accent update process attempts to do.
Disabling User Account Control is a guaranteed mechanism to allow the Service Accent update process to run correctly. Even logging in as an administrator doesn't always work because Windows Vista runs at a higher level than the Administrator account and User Account Control will still interfere with the Service Accent update process.
If you want to turn off User Account Control, visit the article on the Microsoft Technet website here