1) I would try a different torrent program:
http://www.vuze.com/
2) Next I would try ultrasurf to get around blocks:
http://www.ultrareach.com/
^^ Both are well under 4mb
In order to fix this, we need to think like an admin...and find all of the ways he could have blocked files.
Next, lets make sure that the block is not really on the computer:
1) turn off windows firewall
2) reset Internet options
Does it give any type of error when you try to download over 4mb?
Have you tried booting into safe mode?
(While computer is starting up, press F8)
Can you tell us what OS the computer is running?
Try restarting your computer and in the Internet options, add the link for the download to the list of trusted sites?
You are using IE correct?
Is this a wireless connection, or is it coming from a cord?
....go into your network adapters and start looking at the properties.
You might want to look up the commands for cleaning your sockets in the CMD.
Also, check out the host file:
http://en.wikipedia.org/wiki/Hosts_file
Make sure the admin did not do anything funny to it ^^