ERROR: Unable to open file or directory

I have tried redownloading it and everything. It was working fine yesterday just today it comes up with
Scan Started Wed Dec 19 17:02:16 2007
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ERROR: Unable to open file or directory

----------- SCAN SUMMARY -----------
Known viruses: 177764
Engine version: 0.91.2
Scanned directories: 0
Scanned files: 0
Skipped non-executable files: 0
Infected files: 0

Data scanned: 0.00 MB
Time: 7.735 sec (0 m 7 s)
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Completed
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It does this on all the drives.