The reboot loop problem some people are having has nothing to do with WB anti piracy!  It happens when a core bit of WB (the same bit which made WB auto start on login on WB4) has its registry keys zapped by an app on the users PC.  Usually an anti spyware app which is incorrectly assuming WB is spyware and not informing the user what has happened.  As it happens I believe the IE7 beta is having a similar problem with those overly aggressive apps.  It can also happen if the user is trying to bypass the XP activation system, but thats due to the PC appearing to be in safe mode and so WB is disabling itself.

Now onto your problem.  If WB is failing to start after a login then fastload.dll is either missing on the disk or its registry entries are missing.  Are you installing WB from a standalone exe or from SDC?  If you are just extracting a zipped copy of the directory then that will not work as the registry keys will not be being set.

As a workaround, you could put a shortcut to wbload.exe in your startup group

Again I should stress that the number of reported problems due to copy protection is near 0 if you discount those people who used the warez copy of WB.  A few people have SDC accounts which have an error which causes SDC to fail to activate the products and occasionally someone hits the activation limits and Stardock reset them for them, but thats it.

The trial version doesn't even have the activation system, just a simple 60 day timeout which is expected given its a 60 day trial.