jtreg in Windows keeps a minimum set of environment variables which doesn't include TMP or TEMP. The result is that Java will assign C:\Windows as the value of system property "java.io.tmpfile". In Windows Vista, this directory is protected and not writable by normal users, and a whole bunch of tests failed.

This is true for both jtreg 2.1.6 and the latest version 3.2.2_02 night builds.

Ref: How Windows determine the result of GetTempPath() (which Java uses for java.io.tmpfile)
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/fs/gettemppath.asp