That error is something that has snuck into the .09 release that we can't explain. At no time does the code remove any cookies. The really odd thing is that it isn't consistent either. I've got two separate DNN installs on my server. One for a fairly large site that I host and one for my personal and family sites. Both installs get a decent number of visits and repository downloads but only one portal throws that error. Which makes debugging for Steve a real pain in the rear. Anyways, I did some searching on the ASP.NET forums and found that if you changed cacheRolesInCookie="true" to "false" in your web.config that the error went away. From what I can see there have been no adverse effects to it and Steve was going to check with the Core team about any repercussions but I haven't heard yet. So make the change at your own risk.

As for the 0kb File size, I'm not sure if it's related or not to the error. I know Nina was having the same problem and that Steve was working with her on it but I don't know if the problem was solved or not.

RE: Blowery compression.... I thought you might be on to something as I knew I had it running on the site that was having problems but couldn't remember if I set it up on the other one. I just remoted into the webserver and, alas, I'm running it on both. I'll take my laptop home with me tonight with the intent of running WinMerge to the two web.configs just to make sure they're both setup the exact same way.