NetPositive’s author offers this tip on a potential cookie bug.
I’ve found an easily fixable problem that likely affects a lot of NetPositive users. This problem will be corrected in NetPositive 2.2, but if you’re running something earlier (including 3.0d3), this tip applies to you.
Lots of sites that use Microsoft IIS servers and cookies (I know that www.staples.com, www.towerrecords.com, and www.cdpoint.com are examples) will incorrectly report that the browser does not support cookies.
The problem is due to the fact that NetPositive reports to the server that it is running on BeOS, and the server, seeing an OS that it does not expect, actually fails to send the browser one of the cookies that it is later looking for. This problem is easily corrected by modifying the browser information that NetPositive sends to not include the OS. [Editor’s note: The unfortunate side effect of this fix is that page views will not appear in site’s traffic logs as BeOS visits, and it’s nice to be counted. I suggest applying this fix only if you’re having cookie problems.]
If you’re being bitten by this or other cookie problems, then QUIT ALL RUNNING COPIES OF NETPOSITIVE (very important), open up a Terminal window, and type in the following two lines:

 rmattr BrowserString ~/config/settings/NetPositive/settings
addattr -t string BrowserString "Mozilla/4.0 (compatible; NetPositive/2.1.1)" ~/config/settings/NetPositive/settings 

(Note that the last two lines there need to be entered on a single line in the Terminal).
Normally, I laugh at Microsoft conspiracy theorists, but some days, you gotta wonder. To be honest, though, I’d bet a lot of money that this is an innocent oversight on Microsoft’s part and is nothing sinister.