I see this is a somewhat common problem but I haven't come across anyone having the same error message as I do. That being: System extension cannot be used The system extension /System/Library/Filesystems/ufsd_NTFS.fs/Contents/Resources/ufsd_NTFS.kext was installed improperly and cannot be used. Please try reinstalling it, or contact the products vendor for an update. To re-state external NTFS worked on previous system and now I get the above error. Since then I have upgraded paragon and MacFUSE. After MacFUSE upgrade I'm not getting the above error message any more but also the NTFS HD won't recognize.I also have NTFS 3-G and NTFS for MAC OSX. DO I maybe need to get rid of some of these (conflicts with each other?) In similar 10.7 problems Parallels won't start up either. Suggestions? Wishing I hadn't upgraded to 10.7 yet.