There is now a new wallet released https://sourceforge.net/projects/mjollnircoin/files/releases/0.8.7.1/

This is a bugfix release for version 0.8.7.0

Changes:

The checkpoint for block 42742 was wrongly added in 0.8.7.0, this prevented (new) users to synchronize with the block chain
(The wallet starts with checkpointing enabled)

Thanks to rgm108 for reporting the problem! 


Windows wallet is released, Mac OS X and others follow soon.