Well the alert was for Malware Was Found so not quite the same as a detection with the anti-rootkit scan. Though the rootkit-gen malware name is a little off-putting, the -gen I believe indicates that this is a generic signature trying to catch many fish with the one hook so to speak, so there is a possibility that is is not a god detection or a misnamed detection which should be an adware one.
Though there are many VT detections there is a great spread of what it might be but a majority going for mywebsearch, I would have to think even on these results do I want that program or is there another that does the same task without the mywebsearch ?
However, I think it requires further analysis and should be sent to avast.
Send the sample to virus@avast.com zipped and password protected with the password in email body, a link to this topic might help and possible false positive or misnamed malware in the subject.
