Win XP/2k infected with W32/Nachi-A !!

Hi,

I just installed XP on a number of machines and Sophose 3.72 is reporting that they are infected with W32/Nachi-A. The infected file is dllhost.exe which resides in c:\winnt\system32\wins directory. They are newly built and haven’t been used at all how did they get infected?

Even some of the older win2k pro machines are also infected.

Are they really infected or is it just a bogus virus that sophos thinks is W32/Nachi-A?

Please help