There have been several posts about this subject.
I have the same probs on a NW 6.0 sp4 server with
iFolder 2.1.3.
To me it seem that this is a pure client issue.
On a XP-pc with Sun:s java 1.4.2 (and another with 1.4.1)
it doesn't work.
But on a XP-pc without Sun:s java it works ok.

After a little troubleshooting in Sun:s logs and on their
website i found out the following:
If you edit .\lib\security\java.policy -file on the client and
puts in a statement
permission java.io.FilePermission "<<ALL FILES>>", "read, write";
under the "Grant (" -section it works fine. If you just have read you
can upload but not download.

Has anyone tested this?
What inpact does it have on other "java-apps".
Is there a possible security-risk?
Can you spec that only iFolder-web can do this?