When the agent runs as the system, the param for java.io.tmpdir defaults to C:\WINDOWS\TEMP\<BUILD-KEY> and the build works just fine.
When I run the agent as a user (trying to get around permissions issues with writing) the param for java.io.tmpdir defaults to "C:\Documents and Settings\<user-name>\Local Settings\temp\<BUILD-KEY>"

When the build runs, the first task that runs an Ant script I get a message that says:

BUILD FAILED
Target "and" does not exist in project "<project-name>"

Even though I see that the param being passed is in quotes so the space in the path should be taken care of, that's the only "and" I can find in my log. In the build script "and" does not appear anywhere, not even embedded in some other word.