IIS 6.0's auto-compression feature is driving me nuts.  For some reason, my RSS files are being served compressed even when client didn't ask for it via HTTP Content-Encoding header.  I even got Port80's ZipEnable to disable compression just for RSS files but that didn't work consistently so I just disabled compression for all static contents.  Maybe Port80 should have named their product ZipDisable.

Update:

Eeek.  Even disabling compression for everything via ZipEnable doesn't work.  Looks like it's time to explore the IIS 6.0 registry settings.