Invalid target issues

Hello, as this was, at least for me, a DK specific issue I'm posting it here.
Today, in VOA, I was unable to use any attack other than macroed Scourge Strike. Each target showed invalid target message for every spell. Tried relogging, other spec worked fine, relogged again and it remained the same.
In the end, what fixed it was to add spells to macros (autoattack or rune strike), couldn't even click them from the spellbook.

Is this me-specific? Known? Should I post it on the bugtracker?

Check that your alt key is not stuck.