That is more of a Windows problem, not a Boinc problem:

Note: These errors occur because Windows has lost its internal path to the correct BOINC.MSI installer file. It's really a Windows problem, not so much a BOINC problem. No need to complain that BOINC needs to fix this, as BOINC cannot fix problems that are made by Windows!

FAQ: Windows Installer Error 1706: Setup cannot find the required files / 1714: older version cannot be removed / BOINC.msi cannot be found / The feature you are trying to use is on a network resource that is unavailable / Error 1325. is not a valid short name

Don't ever post your email address to forum's as it'll be picked up every bot under the sun, and you'll just get loads of SPAM.

Claggy

Specifically, "the correct boinc.msi installer file" that it's looking for is the *old* version, needed to uninstall the previous version of BOINC before the new one can be installed.

Windows has responsibility for keeping that old file safe: it's nothing to do with the new version of boinc.msi that you've just downloaded.

Reposting Doug's original post, but with his email address removed. We wouldn't want him to be the target of all that unnecessary spam.

Installing the latest version, even after total uninstall and deletion of temp internet files as suggesting the oh, so insulting FAQ section....installation gets as far as User Account Authorization and unpacking files, then cannot find the .msi file it needs. I've run this as an administrator and just from the normal SETI/BOINC upgrade. At this point, I don't have BOINC on my system and never will. I need a private email to xxx@xxx.xxx from a system administrator to explain how to fix this. Otherwise, SETI can find other computing help. Sorry, but this kind of installation bug annoys the hell out of me.