While it may be a false positive, earlier versions of Start11 did not have this malicious coding.
Again, if you downloaded it from Stardock's servers, there is no malicious coding in any version. That is guaranteed. Therefore, it is a false positive and you can either whitelist it or turn off your antiviral while downloading and installing, as recommended by Stardock.
In any multi-antiviral scan, one can receive one or more positive/false positive result. Generally, if only one is positive out of many antiviral engines it can be ignored especially if the software is relatively new. One should be more suspicious if multiple engines report it as a positive, or if one downloads the software from a website other than the original developer's.
Stardock and its servers haven't failed me and its customers in 20 years.