I'm not sure what the right forum for this is, here, or in the Technical forum, but I figure it'll get read more here, so I'm posting here...
My computer (Windows 7 64 bit) was acting strange so I just ran a full virus scan. It detected two viruses and one of them just happened to be in the blockchain. It was detected in Bitcoin\Blocks\blk00129.dat. Those of you running full nodes, especially on Windows, this would be a good time to run a virus scanner. Avast caught this, I can't comment on any others.
Then your virus scanner setting must be wrong, don't scan all files, just executable files.
Not a great idea either if you're relying on a virus scanner to keep you safe. Malicious scripts can be run by opening non-executable files as well such as Word documents, Excel spreadsheets, PDF's, etc. Virus scanners will sometimes catch these so should not be omitted from scans.
Virus scanners are pretty bad anyways. Making a virus undetectable to any scanner is trivial. I don't even bother installing a virus scanner at all, but rather I monitor my system's services, processes, network connections, etc. If I feel that there is even a remote chance that an application or file is infected, it never leaves its own VM.
Virus scanners are not that stupid, DOC PPT XLS COM EXE VBS etc... are all considered "executable files", and will be scanned. But a .DAT file, you can't execute it by default, unless there's some 3rd party program installed that specifically make .DAT file executable.