HTTP error: 400 Bad Request, no connection to docbase - Archivelink isn't working

The other day we had to move some servers around. But when we were done functional testing showed that an archive link in OAC0 was defective. It showed up with the error

HTTP error: 400 Bad Request, no connection to docbase 'docsap': No repository

I was puzzled, in that we didn't really move the tomcat running the connection. Moving the calling database shouldn't cause this problem either.
It took a while, but after some investigation, we found that this error was preexisiting in our system. So no luck running through the changes.
I looked at the SAP side of things, and the connection hadn't changed in a few years, so it wasn't a change. It had to be a bug. I tried moving the archivelink to the development server. It worked like a charm. So not a bug in SAP then.
As an error 400 meant that an error was received (in this case "no repository") The tomcat service was responding. I would have gotten an error 404 if it had been down. However, just to be on the safe side, I decided to restart the service. It IS running on windows after all.
No joy. Maybe an undocumented firewall change ?
Again, no joy. I checked the documentum server manager on the machine. The archive was available.
Maybe a config change in the documentum server ? I looked at the configfiles, there were some issues, but nothing that should cause problems like this. I fixed whatever was apparent, and restarted the tomcat again.
No joy. I was getting spooked. Was it a priviledge problem ? I looked at the user rights. They were good.

Given that another installation seemed to work, it HAD to be the tomcat. I was about to make the call and start a reinstallation of the service, when I wondered: "What would be the difference between reinstalling and now....." Then it hit me.... The workfiles !!! All that temporary crap. I entered the tomcats work dir and cleaned everything that had to do with my repository. Then I rebooted the virtual instance, and 5 minutes later..... Error gone....

this makes me wonder, if I restart my service, why is it even bothering to read through the old crap ? But never mind, I just put a nice little cleanup script together and placed it in the startup of the service.