system
4
I’ve seen this problems many, many times. And it had always the same cause: avast! itself had this file “in use” (locked). The file could be found in the user’s temp file directory.
You can try to delete all your temporary files. If you can not delete all these files, because they are currently locked (in use, for example by avast!), log on as Administrator and remove them (this should always work).
Let us know if this worked for you.