Hi Svenne,
better late then never, a little reply.
I doubt that adding the hard drive deleted the SKI extension. It is possible though that IDs or labels or addresses where changed as you added the disk causing detection failure. Any ways, you solved it through reinstallation which is in doubt fixing almost all possible problems with most our products. Well done 
Regarding the error message:
The tablet side of IC Pro can not determine wether the SKI is just missing or if there is another connection issue. All it knows is that there is no reply from the other side, leaving troubleshooting to the user (ping would be the next logical step). I am not aware of any remote software (including RTP midi) which has network troubleshooting facilities built in as this is solved better in specialized tools.
Thanks for your understanding.
To prevent further single case posts popping up I am going to lock this thread, if anyone thinks the thread should be reopened please PM me.
Please open a separate thread if you have an issue that has not been solved in the forum already.