It could be the admins putting up the firewall but not wanting to let students know. Given the recent lawsuit of RIAA against students over things like Kazaa I can understand why they'd do it. Alternatively, perhaps -- if they have a caching firewall -- it's getting full so fast that it can't deal with the load. And that may be causing the download.

It could also be the ISP they get their pipe from. Again, for the reason of not wanting to deal with RIAA or just to limit the use of downloads. Kazaa and such are big pipe fillers and lots of ISPs, if they detect that activity, are trying to find ways to reduce it as it affects their networks as a whole and not just one segment.

The last possible thing could be that perhaps something in Kazaa has changed (I don't use it so I don't know if they have monitoring software that could be impeeding it).

I'd be quite surprised if your Admins would knowing allow the use on campus of Kazaa and wonder if they have an AUP. If they do and it doesn't allow it, they have every right to stop the flow.

Do you know what kind of firewall they are using? Checkpoint, ISA, Pix?