try this: found at
Open Explorer (Win-E keyboard shortcut)
Go to Organize -> Folder and search options -> View tab -> Make sure “Show hidden files, folders, and drives” is CHECKED. Click OK.
Navigate to: C:\Users\YOUR_ACCOUNT_NAME\AppData\LocalLow\Sun\Java\Deployment\cache\6.0
Delete all the numbered folders in the above directory.
Re-run Windows Backup.
Wasn’t that easy?
It seems that what happens is that you get some kind of Java malware (or what is reported as malware) on your puter. It is stored in Java’s cache directory. Your security software sees it, and it claims to delete it. But, either something goes wrong, or it doesn’t quite remove all copies of the baddie, which then causes a problem with Volume Shadow Copy (which is more or less Window’s “file change history” feature that makes things like Previous Versions and Windows Backup work nicely and efficiently).
So, just delete the contents of the Java cache folder, and your problem is gone.
If the above solution doesn’t work, note what malware your antivirus app is finding, and where it is located. Manually delete the contents of that directory, and try Windows Backup again.
Hopefully, this little tip will save you some time and aggravation!