Did a search on this, but none of the things suggested in the various threads I found solved the problem.
But anyway, my first month of Houdini Apprentice ended, and the re-licensing process didn't go over so smoothly. I used the automatic process first. It goes through, tells me that the non-commercial license was successfully installed, but then when I try to start up any of the Houdini programs it again tells me that I have no licenses and that I need to install one again.
I opened up the License Administrator, and the licenses seem to be just fine. I've also checked to make sure I'm running in standalone mode, so that should be fine. Not the case when looking in the server information tab, though. From there, I'm seeing an error message that reads “the License Server may not serve licenses.” and “(Invalid server key).”
Tried uninstalling 8.0.405 and moving to 8.0.410. Same thing.
I've also tried manually entering keys, as suggested in another thread, but Houdini won't let me install over the keys that are already installed (I really wish I knew where the license files were being stored, so that I could just try clearing those completely, so that I could manually enter keys correctly).
I've also tried completely disabling my firewall, to make sure it wasn't interfering with the licensing apps at all. Same thing.

Am I missing something obvious here? :?
I'll probably email my diagnostic info to support, but thought I'd just check in here first.

Thanks

One thing to try is to delete the ‘keys’ folder in your windows folder and try to reinstall. I think someone suggested it in the past and that did the trick.

Why don't you just post your diagnostic info here?

By anychance, do you have changing IP addresses? (eg. using DHCP when connecting to the Internet?)

AdamJ
One thing to try is to delete the ‘keys’ folder in your windows folder and try to reinstall. I think someone suggested it in the past and that did the trick.

Nice, worked for me. For now, at least… Thanks.

edward - Yeah, I am using DHCP. Is that likely to become a problem with Houdini?

Well, I'm not so sure anymore. DHCP used to be a problem because the server code generated (used to) depend on the IP address that it found. So if your IP address suddenly changed, then the server code will change and invalidate your existing keys.

I also have had exactly similar issues with re-installing of my Apprentice license. For some reason , the keys do not automatically take so I have to Manually instal them from Side Effects site. I check my license manager, and everything seems to be validated but when trying to start Houdini, I receive the same errors (“the License Server may not serve licenses” ). I also run Win XP pro. So it seems the issue has to do with Houdini license manager and Windows.