1) Download the latest version of the 7230 software (the Handheld software, not the OS software). There is a Sticky Thread FAQ at the top of the General BlackBerry Discussion forum with the URLs on where to download it from.
2) Execute the file you just downloaded
3) Locate and delete VENDOR.XML from your PCs C: drive
4) Restart Desktop Manager with your BB connected; it should load now.
Good idea to have read up on this before you wiped out your BB.