Alessandro,
For the LabVIEW registry records you may do the following: (NOTE: Make a backup of the registry file before deleting something, because the registry is a very delicate system file)
1. Go to Start >> Run... Type: "regedit" and click enter.
2. Make the backup of the file.
3. Browse through the folder HKEY_LOCAL_MACHINE >> Software >> National Instruments
4. If you see this folder and inside it you see a LabVIEW folder, delete that LabVIEW folder ONLY.
If you don't have any other National Instruments software then you may want to delete also the National Instruments folder, but only in this case. Be careful when deleting registry folders, be sure to select only the folder you want to delete.
Try this and make a reboot of the c
omputer and double check the registry. After having for sure that you have a clean system then install LabVIEW.
If you still found issues when installing LabVIEW you may want to call us or email us, the contact information can be found at www.ni.com/ask in the web.
Good luck!
Nestor Sanchez
Applications Engineer
National Instruments
Nestor