It depends how you did the re-install, was it a full reformat first ?
Also are the backup files being restored clean
But you could check out for the lates MBR threat
[*]Download AntiZeroAccess to Desktop
[*]Double click on it to run it (If running Vista or Windows 7, right click on it and select “Run as an Administrator”)
[*]Type y and press enter to run the scan
[*]Please post AntiZeroAccess_Log.txt contents in your next post. This file is saved in the same location as AntiZeroAccess program.