"Rootkit: hidden file" but Avast says "Error: The request is not supported (50)"

OK, this is confusing. After a full scan, Avast reports a threat in the following file:

C:\WINDOWS\Temp_avast_\unp246044957.tmp
Severity: High
Threat: Rootkit:hiddenfile

If I try to apply an action, I get the following:

Action: Move to Chest
Error: The request is not supported (50)

Action: Delete
Error: The system cannot find the file

Is this perchance a file that was identified earlier by Avast and put in the “chest” and then deleted?

Thanks!

C:\WINDOWS\Temp\_avast_\unp246044957.tmp
looks as the temp file from an avast webscan

Try cleaning your temp files and scan again

TFC - Temp File Cleaner by OldTimer
http://www.geekstogo.com/forum/files/file/187-tfc-temp-file-cleaner-by-oldtimer/
TFC requires a reboot immediately after running. Be sure to save any unsaved work before running TFC.