yes there are actually a few bugs in the wallet.
one thing you can do is resync the wallet from scratch. and it should fix the issue, that does mean to save your wallet.dat file and delete all other files in the working folder leaving only the wallet dat in place. and any configuration files should also remain like the .conf if your using one. when  all other files are deleted and your wallet was turned off... now go ahead and start it again... it should sync and remove many of the bad block errors or the invalid transactions ext and will put you back where you should be.