Alsee writes "Welcome to our first real taste of Trusted Computing: With Vista Enterprise and Vista Ultimate, Service Pack 1 refuses to install on dual boot systems. Trusted Computing is one of the many things that got cut from Vista, but traces of it remain in BitLocker, and that is the problem. The Service Pack patch to your system will invalidate your Trust chain if you are not running the Microsoft-approved Microsoft-trusted boot loader, or if you make other similar unapproved modifications to your system. The Trust chip (the TPM) will then refuse to give you your key to unlock your own hard drive. If you are not running BitLocker then a workaround is available: Switch back to Microsoft's Vista-only boot mode, install the Service Pack, then reapply your dual boot loader. If you are running BitLocker, or if Microsoft resumes implementing Trusted Computing, then you are S.O.L."