Did you just run into a file that is digitally signed by PlusOne System? If so, please read on.
You will probably notice PlusOne System when clicking to run the file. The publisher name shows up as the "Verified publisher" in the UAC dialog as the screenshot shows:

You can view the digital signature details for PlusOne System with the following steps:
Here is a screenshot of a file that has been signed by PlusOne System:

As you can see in the screenshot above, Windows states that "This digital signature is OK". This implies that the file has been published by PlusOne System and that no one has tampered with the file.
If you click the View Certificate button shown in the screengrab above, you can view all the details of the certificate, such as when it was issued, who issued the certificate, how long it is valid, and so on. You can also view the address for PlusOne System, such as the street name, city and country.
Thawte Code Signing CA has issued the PlusOne System certificates. You can also see the details of the issuer by clicking the View Certificate button shown in the screenshot above.
The following are the PlusOne System files I've gathered, thanks to the FreeFixer users.
| Detection Ratio | File Name |
|---|---|
| 1/42 | Top-Search.dll |
Here is the detection names for the PlusOne System files. I have grouped the detection names by each scanner engine. Thanks to VirusTotal for the scan results.
| Scanner | Detection Names |
|---|---|
| Symantec | WS.Reputation.1 |
The detection percentage is based on that I have gathered 42 scan reports for the PlusOne System files. 1 of these scan results came up with some sort of detection. You can review the full details of the scan results by examining the files listed above.
The analysis is done on certificates with the following serial numbers: