Office Home and Business 2010 Access keeps prompting for product key every startup, Problem with Access 2007 runtime engine, msain.dll corrupt or missing

I have Office 2010 Home and Business an my Computer and things for OK for a long time. My ERP-Software which uses Access 2007 runtime engine was up and running for Ages.After installing a new time management software which (Zeitplan), which also seems to be based on Access runtime, problems started.

Starting my ERP-Software failed. An error prompt said "missing or currput msain.dll". Next time it suggested to start Access in Safe Mode, but that did not fix the Problem. The msain.dll was were i expected it to be (OfficeDir\1031). Downloaded the dll from the Internet and replaced the existing one. No changes.
Re-Installed my ERP-Software. No changes.

Did a repair on Office 2010.
No my ERP-Software started to start, but then the Access 2010 splash Screen was shown and it prompted me to enter my Office 2010 Product Key. Entered the key, it was shown as valid, Office activated itself OK. But after a few seconds, i was prompted for the product key again. And again.  And so on.... (Word and Excel did not prompt on Startup. Thei Help box said, they're activated).

I then had a look on the Internet and found out, that Office 2010 Home and Business Edition does not include Access.

How-i-fixed-it:
I found the right hints here (in German): http://www.dims.de/blog/?p=530

I removed Access from the Office 2010 Installation (Control Panel->Add/Remove Programs->Office 2010->Change). I also uninstalled the Access 2007 runtime.

I then re-installed the ERP-Software (which also installed the Access 2007 runtime again).

After that, the ERP-Software was running fine (and also the time Management software). No more product key prompts.

Some other threads about never-ending-product-key-prompt:

http://answers.microsoft.com/en-us/office/forum/office_2010-office_install/after-every-pc-reboot-office-2010-keeps-asking-for/87e2cac0-d8cb-432b-a3d9-8721edf12487?page=1

http://answers.microsoft.com/en-us/office/forum/office_2010-office_install/why-do-i-need-to-enter-product-key-each-time-for/37ef2acf-f6a9-4122-9f1a-f31c815aabf1