I’ve seen it, too. It seems to be fairly common.
I’ve run into several theories about why this might happen.
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Potentially Unprotected Could Mean Several Things
The warning that Microsoft Security Essentials (MSE) throws is actually less than helpful.
“PC Status: Potentially unprotected” can actually happen for several different reasons:
- A scan hasn’t been run in “a while.”
- The malware definition database is out of date.
- The Antimalware Service isn’t running.
More often than not, it’s actually one of the first two.
Theory #1: Malware
Yes, there’s a small possibility that this is a side effect of malware on your machine. Based on how often I see this symptom on clean machines (including my own), I’m skeptical that this is the case.
On the other hand, it’s also better to be safe than sorry, so running up-to-date anti-malware scans might be the first thing to do. Because that is exactly what you’ve been doing and it still returns Microsoft Security Essentials (MSE) to it’s green/Protected state, my opinion is that this is not the case for you.
If the status remains Unprotected or the scans never complete, then I’d absolutely have you take the appropriate steps to remove malware from your machine, as well as uninstalling and re-installing MSE.
Theory #2: CCleaner
There are options in the “Applications” section of the CCleaner computer cleaning tool to clean MS AntiMalware, which I believe means that when selected, CCleaner may delete information that confuses MSE. In fact, it may be as simple as CCleaner removing MSE’s own log files.
The result is that MSE thinks, “Oh, gosh, you’ve never run a scan, so you’re Potentially Unprotected!”
I’ve replicated this by running CCleaner and waiting a while. Eventually (at least for me), MSE reverts to that “Potentially unprotected” message, telling me that I’ve not run a scan for a while, even though it also notes that the last scan was run 25 minutes ago.
If this is the case, you can safely ignore it or configure CCleaner to not clean up the files relating to MS AntiMalware.
Theory #3: Other Anti-malware tools
We do often recommend that you run only one anti-malware tool at a time. Normally, this refers to the real-time scanning capabilities of each coming into conflict. In this case, the theory is that another anti-malware tool is somehow interfering with MSE’s ability to run or remember that it has been run unrelated to real-time scans.
Depending on the other package, it may be as simple as deselecting some of its scanning or privacy options or as extreme as uninstalling the other software completely.
Theory #4: Miscommunication
I believe that there is also the potential for miscommunication between your system and Microsoft’s servers. MSE thinks it’s out of date when it’s not. It could be as simple as the time of day or date being wrong such that MSE gets the automatic update sequence a little confused.
Just update and scan
Because you can run a manual scan to make that notification go away, that might be the simplest solution of all. I know that running a scan just to do this might be time consuming. That’s why I wanted to reassure you that, in all likelihood, everything is actually okay.
Note that the error message is not saying you are unprotected. It’s saying you may be unprotected. In most all of the cases above, you are indeed protected and MSE is just a little confused.
The other approach is simply to ignore it and give it time. MSE should eventually get itself up-to-date and run a scan on its own. It’ll stop complaining about being potentially unprotected … until, of course, whatever causes the issue reoccurs.
Like I said, my belief is that this not a huge issue. I hate to be training people to ignore that “Potentially unprotected” warning, but this time, I believe that might be the most practical solution.