In Emacs 24.4.1 I do not notice any tool tip information.
The *Completions* buffer appears after the M-?. The message buffer has "Type SPC to continue editing." message which I believe comes from the verilog-mode.el code. When the mouse is over the word "initial", in *Completions* buffer, the word is highlighted. I do not notice any other tool tips or other messages.
The CPU does not runaway until some event occurs (any mouse click or key stroke) It appears that whatever input is pressed, the CPU runs away, and the keystroke itself is lost. The *Completions* buffer disappears, and editing can continue. Left unchecked, the runaway process consumes all memory and eventually emacs crashes, but it is not "immediate". Other editing seems to work fine.