Cannot install after being detected as WS.Reputation.1! Is it a virus?
No, it is simply when Symantec products determine a file has a "low reputation". This is normal for a new file, after all it cannot have a high reputation before it is even being used!
Note that the name has now changed to Heur.AdvML.B.
Symantec's explanation on how this works is here:
A developer's view of this situation:
And another developer view:
You can check whether it is indeed a virus by submitting it to the on-line virus submission portals that use tens of virus checkers, e.g.: