Here is another problem I find myself solving at least weekly now:
Problem - any one or more of the following: * Users claim they can log in correctly, get to their "My Home", but as soon as they click on any link they are logged back out. This means they can't post, send PM's, etc.
Cause: Every time I've encountered this scenario, the user's computer was set to the wrong date.
Resolution: Check the date on your computer.
- Windows
1. Double-click on the Time down in the lower right-hand corner of your screen
or
2. Use the Start menu:
Click Start and choose Settings, then Control Panel.
Double-click the Date and Time icon.
- Mac:
1. From the Apple menu, choose Control Panels.
2. Double-click the Date & Time control panel icon.
If the date is wrong, fix it!

The problem is that UBB.threads is placing the cookie on the user's computer, but as soon as they click a link and threads tries to find the cookie, it has already expired (because their computer thinks it's months in the future.)