Spybot is rather dated. Mods here rarely mention it except to uninstall it.
More current scanners are noted by the Moderators and Grif. Read
In short, such used to be OK but now I encounter troubles but this is just one thing, may be others.
Here's the situation:
While downloading some attachment from Yahoo mail (an Open Office document) saving the file fails.
At the same time I realized that when I tried to delete files (I thought maybe there were too many of them in the "download" dir. ) became impossible: Windows denies access.
At the same time creating or copying files is possible.
At the same time deleting files through CMD prompt (using "del" command) is possible.
I was able to restore the system to an earlier date which fixed the problem.
Then I went to download that file again. Saving fails. And deleting is lost again.
I read several links on the topic, but it seems to be different from what I have, suggesting using some utilities, or Administrator account etc.
ALL FILES are this way - I cannot delete ANYTHING anymore.
PS> I did run Avast full scan for viruses, and Spybot full scan for malware. Both came up negative.