Virus on old file?

OK I have this ubot forum profile register tool in my old windows xp machine and been working great...My antivirus was AVG 2009 professional.. Now I have new PC running on windows 7. I am trying to use this piece of tool in my new machine but my AVG 2010 is telling me there is a virus. Because I really need it, I disabled my AVG....and then it is working great..

Is there any possibility that the software was infected? I don't see any reason why.. Both of my PC's are very clean...