Unable to uninstall Backup Exec due to error 1324 "The path C: contains an invalid character."

I have an installation of Backup Exec that I want to move the databse from the local SQL express to a SQL 2008 instance. Unable to do so with the beutility I want to reinstall the installation. Unfortunately I get this in the log

12-11-2012,10:12:33 : FATAL ERROR: Error 1324.The oath C: contains an invalid character.

I have searched the support pages and forums without finding the same problem mentioned before. Similar problems with other paths mentioned and solutions, like fixing the registry InstallPath value, have not fixed the issue.