What does it mean if an receiving address is grey and in Brackets? (in the Transaction overview)

Or if there is (k.A.) in this overview?


Should be delete/backup the wallet.dat and rename wallet.dat.rewrite -> wallet.dat? ....testing.... no that doesn't work...

PS: It doesn't matter to me, because I have about 0.0015 Bitcoins on there anymore, but I wonder....
PPS: hmm..... I try it with an unencrypted "pre 0.4 version" wallet